culture and stimulation of peripheral blood mononuclear cells with the aid of pma and pha - p -- preparation of the messenger rna used to prepare the complementary dna library a cell fraction enriched in peripheral blood mononuclear cells , pbmnc , of the following approximate composition : 70 % of lymphocytes , 25 % of monocytes and 5 % of granulocytes ( cells counted using a coulter model s . plus iv cell counter ), is taken from bags of peripheral blood ( obtained from three healthy volunteers in a blood transfusion center ) which has first undergone cytapheresis and a ficoll ® gradient ( gauchat et al ., 1989 , eur . j . imm ., 19 , 1079 ). the cells are collected in a 250 ml flask and then centrifuged for 10 min at 37 ° c . the supernatant is removed and the cell residue is rinsed with 50 ml of a medium based on glucose , mineral salts , amino acids and vitamins , called rpmi medium ( rpmi 1640 medium from gibco brl ), and then centrifuged again under the same conditions . the cell residue is then taken up with 500 ml of rpmi medium complemented with 10 % of fetal calf serum ( gibco brl -- ref . 013 - 06290h ), to which 10 units of penicillin and 10 μg of streptomycin ( solution of penicillin / streptomycin from gibco , ref . 043 - 05140d ) have been added per ml of medium and to which l - glutamine ( gibco brl -- ref . 043 - 05030d ) has been added to a final concentration of 2 mm . part of the cell suspension is divided up for separation of the adhesive cells and the non - adhesive cells , at a rate of about 100 ml per dish , in four large square culture dishes ( 245 × 245 × 20 mm -- nunc -- ref . 166508 ), and incubated for 1 h at 37 ° c . it is in fact known that the majority of monocytes adhere to the culture dish , whereas the majority of lymphocytes remain in suspension . the non - adhesive cells are sucked off with a pipette and cultivated in falcon - type culture flasks with a surface area of 175 cm 2 , in the presence of rpmi medium complemented as described above , to which 10 ng / ml of phorbol 2 - myristate - 3 - acetate ( pma ) ( sigma -- ref . p8139 ) and 5 μg / ml of phytohemagglutinin ( pha - p ) ( sigma -- ref . l8754 ) have been added , at 37 ° c , in the presence of 5 % of co 2 , for 24 h . 100 ml of rpmi medium complemented as described above , to which 10 ng / ml of pma and 5 pg / ml of pha - p have been added , are added to the adhesive cells . the cells are incubated at 37 ° c ., in the presence of 5 % ( v / v ) of co 2 , for 5 h . the remainder of the cell suspension , hereafter called the whole cells , is divided up into 4 large square culture dishes and incubated in the presence of rpmi medium complemented as described above , to which 10 ng / ml of pma and 5 μg / ml of pha - p have been added , at 37 ° c ., in the presence of 5 % ( v / v ) of co 2 , for 5 h in the case of the first two dishes and 24 h in the case of the other two . about 2 h before incubation ends , 10 μg / ml of cycloheximide ( sigma -- ref . c6255 ) ( a translation inhibitor which increases the stability of the rnas of the cytokinins : cf . t . lindsten et al ., 1989 , science , 244 , 339 - 344 ) are added to the culture medium of these different cells and incubation is continued for 2 h at 37 ° c . the adhesive cells are washed twice with pbs ( phosphate buffered saline , ref . 04104040 -- gibco brl ) and then scraped with a rubber scraper and centrifuged . this gives a cell residue called residue a . for the non - adhesive cells , after the flask containing the cell suspension has been shaken , the cell suspension is removed and centrifuged . this gives a cell residue called cell residue na . for the whole cells , the adhesive fraction is washed twice with pbs , scraped as above and then centrifuged . the non - adhesive fraction is centrifuged . the two cell residues obtained will subsequently be combined . this combination is called cell residue t ( 5 h ) in the case of the whole cells incubated for 5 h , and t ( 24 h ) in the case of the whole cells incubated for 24 h . the cell residues a , na , t ( 5 h ) and t ( 24 h ) are frozen and kept at - 80 ° c . each frozen cell residue is suspended in a lysis buffer of the following composition : guanidine thiocyanate 5 m , tris ( hydroxymethyl ) aminomethane 50 mm ph 7 . 5 and edta 10 mm . the suspension is sonicated using an ultra turrax ® no . 231 256 sonicator ( janke and kunkel ) at maximum power for four 20 s cycles . β - mercaptoethanol is added to 0 . 2 m and a 30 s sonication cycle is carried out . lithium chloride is added to 3 m . the suspension is cooled to 4 ° c . and left to stand at this temperature for 48 h . the rna is then isolated by centrifugation for 60 min . the rna residue is washed once with a 3 m solution of lithium chloride , centrifuged again and then taken up in a buffer of the following composition : sds 1 %, edta 5 mm and tris - hcl 10 mm ph 7 . 5 , to which 1 mg / ml of proteinase k ( boehringer mannheim , gmbh ) has been added . after incubation at 40 ° c . for 1 h , the rna solution is extracted with a phenol / chloroform mixture . the rna contained in the aqueous phase is precipitated at - 20 ° c . with a solution of ammonium acetate of final concentration 0 . 3 m and 2 . 5 volumes of ethanol . the mixture is centrifuged at 15 , 000 g for 30 min and the residue is retained . the residue is taken up in 1 ml of a buffer of the following composition : tris - hcl 10 mm ph 7 . 5 and edta 1 mm , called te buffer , and suspended by agitation on a vortex . type 3 oligo dt - cellulose ( marketed by collaborative research inc ., biomedicals product division ) is prepared according to the manufacturer &# 39 ; s recommendations . the rna is deposited on the oligo dt - cellulose , shaken gently to suspend the beads and then heated for 1 min at 65 ° c . the suspension is adjusted to 0 . 5 m with nacl and then shaken gently for 10 min . the suspension is then centrifuged for 1 min at 1000 g , the supernatant is removed and the residue is washed twice with 1 ml of te buffer containing 0 . 5 m nacl . the supernatants are removed . the polyadenylated fraction of the rnas ( consisting of the messenger rnas ) is eluted by suspending the beads in 1 ml of te buffer , then heating this suspension at 60 ° c . for 1 min and then shaking for 10 min on a tilting plate . the suspension is then centrifuged for 1 min at 1000 g , making it possible to recover the supernatant containing free messenger rnas in solution . the above series of operations ( as from elution ) is repeated twice . the supernatants thus obtained are pooled , the residual beads are removed by centrifiguation and the supernatant is precipitated with 3 volumes of ethanol and a solution of nacl of final concentration 0 . 3 m . starting from the cell residues a , na , t ( 5 h ) and t ( 24 h ), this procedure gives four samples of rna - poly a + , hereafter referred to as rna - poly a + - a , rna - poly a + - na , rna - poly a + - t ( 5 h ) and rna - poly a + - t ( 24 h ). preparation of a complementary dna library enriched in sequences specific for peripheral blood mononuclear cells the strategy employed uses fragments obtained from pre - existing plasmids available to the public , and fragments synthesized by the techniques now in common use . the cloning techniques employed are those described by t . maniatis , e . f . fritsch and j . sambrook in &# 34 ; molecular cloning , a laboratory manual &# 34 ; ( cold spring harbor laboratory , 1984 ). the oligonucleotides are synthesized using a biosearch 8700 dna synthesizer . the following description will be understood more clearly with reference to fig1 a . this plasmid was constructed by successive ligation of the following elements : a )-- a pvuii -- pvuii fragment -- symbolized by +++++++ in fig1 a -- of 2525 bp , obtained by complete digestion of plasmid ptz18r ( pharmacia ) with the restriction enzyme pvuii . this fragment contains the origin of replication of phage f1 ( indicated as ori f1 in fig1 a ), a gene ( indicated as amp r in fig1 a ) carrying ampicillin resistance and the origin of replication ( indicated as ori pbr322 in fig1 a ) permitting the replication of this plasmid in e . coli . the first pvuii blunt site disappears through ligation with the ecorv blunt site ( which also disappears ) of the fragment described in g ). b )-- a pvuii - hpai fragment -- symbolized by  in fig1 a -- of 1060 bp , of type 5 adenovirus dna between position 11299 ( pvuii restriction site ) and position 10239 ( hpai restriction site ) ( dekker and van ormondt , gene , 27 , 1984 , 115 - 120 ) containing the information for the rnas va - i and va - ii . the hpai blunt site disappears through ligation with the pvuii blunt site ( which also disappears ) of the fragment described in c ). the apai site in position 11218 was removed by cleavage with the enzyme apai , exonucleolytic treatment with the dna polymerase of phage t4 and religation . c )-- a pvuii - hindiii fragment -- symbolized by in fig1 a -- of 344 bp , derived from sv40 dna obtained by complete digestion with the restriction enzymes pvuii and hindiii . this fragment contains the origin of replication and the early promoter of sv40 dna ( ref . b . j . byrne et al ., proc . ntl . acad . sci . u . s . a . ( 1983 ) 80 , 721 - 725 ). the hindiii site disappears through ligation with the site binding to hindiii of the fragment described in d ). d )-- a synthetic &# 34 ; site binding to hindiii &# 34 ;-- hindiii fragment -- symbolized by ══ in fig1 a -- of 419 bp , whose sequence , given in fig1 b , contains a sequence similar to the untranslated 5 &# 39 ; sequence of htlv1 ( r . weiss et al ., &# 34 ; molecular biology of tumor viruses &# 34 ;-- part 2 -- 2nd edition -- 1985 -- cold spring harbor laboratory -- p . 1057 ) and the distal intron of the mouse α - globin gene ( y . nishioka et al ., 1979 , cell , 18 , 875 - 882 ). e )-- a synthetic hindiii --&# 34 ; site binding to bamhii &# 34 ; fragment -- symbolized by xxxxxxx in fig1 a -- containing the promoter of the rna polymerase of phage t7 as well as a polylinker containing especially the apai and bamhi cloning sites ( seq id no : 18 ): apai - ▾ agcttgtcgactaatacgactcactatagggcggccgcgggcccct - acagctgattatgctgagtgatatcccgccggcgcccgggga ▴ hindiii bamhi site binding to bamhi ▾ ▾ gcaggaattcggatcccccgggtgactgact - cgtccttaagcctagggggcccactgactgactag f )-- a bamhi - bcli fragment -- symbolized by ▴▴▴▴. tangle - solidup .▴▴ in fig1 a -- of 240 bp , this being the small fragment obtained by complete digestion of sv40 dna with the enzymes bcli and bamhi and containing the sv40 late polyadenylation site ( m . fitzgerald et al ., cell , 24 , 1981 , 251 - 260 ). the bamhi and bcli sites disappear through ligation respectively with the &# 34 ; site binding to bamhi &# 34 ; of the fragment described in e ) and the bamhi site ( which also disappears ) of the fragment described in g ). g )-- a bamhi - ecorv fragment -- symbolized by oooooo in fig1 a -- of 190 bp , this being the small fragment derived from plasmid pbr322 after complete digestion with the enzymes ecorv and bamhi . plasmid pse1 therefore contains the elements necessary for its use as a cloning vector in e . coli ( origin of replication in e . coli and ampicillin resistance gene , originating from plasmid ptz18r ) and as an expression vector in animal cells ( promoter , intron , polyadenylation site , origin of replication of sv40 ), and for its single - stranded copy with a view to sequencing ( origin of replication of phage f1 ). 2 ) constitution of a complementary dna library enriched in sequences specific for peripheral blood mononuclear cells the cloning technique used is the one described by caput et al . ( primer - adapter technique : caput et al ., proc . natl . acad . sci . ( u . s . a . ), 1986 , 83 , 1670 - 1674 ). it consists on the one hand in digesting vector pse1 with apai , adding a polydc tail to the protuberant 3 &# 39 ; end and then digesting the resulting plasmids with the endonuclease bamhi . the fragment corresponding to the vector is purified on a column of sepharose ® cl4b ( pharmacia ). it therefore comprises a polydc tail at one end , the other end being a sticky end of the bamhi type . on the other hand , the rna - poly a + s obtained at the end of section 1 are subjected to reverse transcription starting from a primer having the following sequence ( seq id no : 19 ): thus , at their 5 &# 39 ; end , the cdnas have the sequence gatcc complementary to the bamhi sticky end . the rna - dna hybrids obtained by the action of reverse transcriptase are subjected to alkaline hydrolysis , which makes it possible to remove the rna . the single - stranded cdnas are then subjected to a treatment with terminal transferase so as to add polydgs at the 3 &# 39 ; end , and purified by 2 cycles on a column of sepharose ® cl4b . these cdnas are hybridized with rna - poly a + originating from cells of the cos3 line ( monkey kidney cell line expressing sv40 t - antigen : cf . y . gluzman , 1981 , cell , 23 , 175 - 182 , prepared as described in section 1 . 2 ). the unhybridized cdnas are isolated ( fraction enriched in dna complementary to the messenger rnas specific for peripheral blood mononuclear cells ). these cdnas are inserted in single - stranded form into vector pse1 . a second oligonucleotide ( the adapter ), complementary to the primer , is necessary for generating a bamhi site at the 5 &# 39 ; end of the cdnas . after hybridization of the vector , the cdna and the adapter , the recombinant molecules are annealed by the action of the ligase of phage t4 . the single - stranded regions are then repaired by the dna polymerase of phage t4 . the resulting pool of plasmids is used to transform the strain e . coli mc1061 ( casabadan and s . cohen , j . bact . ( 1980 ) 143 , 971 - 980 ) by electroporation . starting from 5 μg of the rna - poly a + s of peripheral blood mononuclear cells obtained at the end of section 1 , of the following composition : rna - poly a + - a : 0 . 5 μg , rna - poly a + - na : 2 μg , rna - poly a + - t ( 5 h ): 2 μg and rna - poly a + - t ( 24 h ): 0 . 5 μg , the single - stranded complementary dna labeled with 32 p - dctp ( the complementary dna obtained has a specific activity of 3000 dpm / ng ) is prepared with the synthetic primer of the following sequence ( seq id no : 19 ) ( comprising a bamhi site ): in a volume of 100 μl . after incubation for 30 min at 46 ° c . with 100 units of the enzyme reverse transcriptase ( genofit -- e1 022 ), 4 μl of edta 0 . 5 m are added . a first extraction is carried out with phenol ( saturated with te buffer ) and then a second with chloroform . the following are added : 10 μg of calf liver transfer rna , and 1 / 10 volume of a 10 m solution of ammonium acetate and 2 . 5 volumes of ethanol to precipitate the complementary dna . the mixture is centrifuged , the residue is dissolved in 30 μl of te buffer and the small molecules such as salts , phenol and chloroform are then removed by exclusion chromatography on a column of polyacrylamide p10 ( biogel p10 - 200 - 400 mesh , ref . 1501050 -- biorad ). 4 . 6 μl of a 2 n solution of naoh are added , incubation is carried out for 30 min at 68 ° c ., 4 . 6 μl of 2 n acetic acid are then added and the solution obtained is passed over a column of polyacrylamide p10 . the complementary dna is extended at the 3 &# 39 ; end with a dg &# 34 ; tail &# 34 ; using 66 units of the enzyme terminal transferase ( pharmacia -- 27073001 ). incubation is carried out for 30 min at 37 ° c . and 4 μl of edta 0 . 5 m are then added . to remove the synthetic primer , the complementary dna is purified on two successive columns of 1 ml of sepharose ® cl4b ( pharmacia ) equilibrated with a solution of naoh 30 mm / edta 2 mm . the first three radioactive fractions ( of about 80 μl each ) are combined and precipitated with 1 / 10 volume of a 10 m solution of ammonium acetate and 2 . 5 volumes of ethanol . the amount of complementary dna is 1 μg . the residue of complementary dna is suspended in 25 μl of te buffer , 15 μg of rna - poly a + extracted from cells of the cos line are added , followed by 1 / 10 volume of a 3 m solution of nacl and 2 . 5 volumes of ethanol , and the mixture is left to precipitate at - 20 ° c . it is centrifuged , the residue is washed with 70 % ethanol , dried and dissolved in 5 μl of a buffer of the following composition : tris - hcl 0 . 1 m ph 7 . 5 , nacl 0 . 3 m and edta 1 mm , the solution obtained is placed in a capillary tube , which is sealed , and incubation is then carried out at 65 ° c . for 40 h . the contents of the capillary are diluted in 100 μl of te buffer to which 300 μl of sodium phosphate buffer 50 mm ph 6 . 8 are added . the solution obtained is passed over a column of hydroxyapatite ( biorad , ref . 130 . 0520 ) at 60 ° c ., equilibrated with this phosphate buffer . the single - stranded material ( the unhybridized complementary dna ) and the double - stranded material ( the cos messenger rna hybridized with the complementary dna ) are separated by passing a gradient of 0 . 1 m to 0 . 2 m phosphate buffer through the column of hydroxyapatite . the fractions corresponding to the single - stranded complementary dna are combined ( 25 % by weight of the cdna eluted , which corresponds to an approximately 4 - fold enrichment in sequences specific for peripheral blood mononuclear cells ), 20 μg of transfer rna are added and the total volume is precipitated with 1 / 10 volume of a 10 m solution of ammonium acetate and 2 . 5 volumes of ethanol . the mixture is centrifuged , the residue is dissolved in 200 ml of te , the residual phosphate is removed on polyacrylamide p10 and the solution is precipitated again with 1 / 10 volume of a 10 m solution of ammonium acetate and 2 . 5 volumes of ethanol . the residue is dissolved in 30 μl of a solution of naoh 30 mm , edta 2 mm . the complementary dna is loaded on to a column of sepharose ® cl4b ( pharmacia ) of capacity 1 ml , equilibrated with a solution of naoh 30 mm , edta 2 mm , in order to remove the remaining synthetic primer . the first 3 radioactive fractions , of about 80 μl each , are combined . the cdna contained in these fractions is precipitated with 1 / 10 volume of a 10 m solution of ammonium acetate and 2 . 5 volumes of ethanol . the amount of complementary dna recovered in this way is 20 ng . f ) pairing of cloning vector pse1 and the complementary dna in the presence of the adapter the mixture is centrifuged , the residue is dissolved in 33 μl of te buffer , 5 μl ( 125 ng ) of cloning vector pse1 , 1 μl ( 120 ng ) of the adapter of the following sequence ( seq id no : 20 ) ( comprising an apai site ): and 10 μl of a 200 mm solution of nacl are added , incubation is carried out for 5 min at 65 ° c . and the reaction mixture is then left to cool to room temperature . the cloning vector and the single - stranded cdna are ligated in a volume of 100 μl with 32 . 5 units of the enzyme dna ligase of phage t4 ( pharmacia , ref . 270 87002 ) overnight at 15 ° c . the proteins are removed by extraction with phenol followed by extraction with chloroform , and 1 / 10 volume of a 10 m solution of ammonium acetate and 2 . 5 volumes of ethanol are then added . the mixture is centrifuged and the residue is dissolved in a buffer of the following composition : tris acetate ph 7 . 9 33 mm , potassium acetate 62 . 5 mm , magnesium acetate 1 mm and dithiothreitol ( dtt ) 1 mm . the second strand of complementary dna is synthesized in a volume of 30 μl with 30 units of the enzyme dna polymerase of phage t4 ( pharmacia : ref . 27 - 0718 ) and a mixture of the four deoxynucleotide triphosphates datp , dctp , dgtp and dttp , as well as two units of the protein of the 32 gene of phage t4 ( pharmacia : ref . 27 - 0213 ), for 1 h at 37 ° c . extraction is carried out with phenol and the traces of phenol are removed using a column of polyacrylamide p10 ( biogel p10 - 200 - 400 mesh -- ref . 15011050 -- biorad ). e . coli mc1061 cells ( clontech ) are transformed with the recombinant dna obtained above by electroporation using a biorad gene pulser ® apparatus ( biorad ) run at 2 . 5 kv under the conditions prescribed by the manufacturer , and the bacteria are then grown for 6 h 30 min in so - called lb medium ( sambrook , op . cit .) of the following composition : bactotryptone 10 g / l , yeast extract 5 g / l and nacl 10 g / l , to which 100 μg / ml of ampicillin have been added . the number of independent clones is determined by plating a 1 / 1000 dilution of the transformation before amplification on a dish of lb medium to which 1 . 5 % ( w / v ) of agar and 100 μg / ml of ampicillin have been added , this being called lb gelose medium hereafter . the number of independent clones is 500 , 000 . screening of the subtracted complementary dna library and selection of clone nc28 1 ) creation of the replicas of the bacterial colonies of the cdna library on a nylon filter about 40 , 000 recombinant bacteria of the cdna library are distributed on ( 245 × 245 ) mm petri dishes containing lb gelose medium ( about 2000 colonies / dish ). starting from each of these dishes , the colonies are transferred on to a nylon membrane ( hybond n - amersham ) by laying the membrane on the surface of the dish and making reference points by piercing the membrane with a needle . the membrane is then removed and laid on the surface of a new petri dish containing lb gelose medium . this is left to stand for a few hours at 37 ° c . for regrowth of the colonies . starting from this first membrane , two replicas are created on new membranes ( moistened beforehand by being laid on lb gelose medium ) by successive contacts with the first membrane . the resulting replicas on membranes are finally laid on dishes of lb gelose medium and incubated overnight at 30 ° c . the replicas on membranes are laid , with the colonies facing upwards , on a sheet of whatman 3mm saturated with a solution of the following composition : naoh 0 . 5 m and nacl 1 . 5 m , for 5 min , which makes it possible to lyze the bacteria and fix the dna . the replicas on membranes are then placed on a second sheet of whatman 3mm , saturated this time with a neutralizing solution of the following composition : nacl 1 . 5 m and tris - hcl ph 8 0 . 5 m , for 5 min . the replicas on membranes are then immersed in a 2 × ssc solution ( composition of the ssc solution : nacl 0 . 15 m and sodium citrate 0 . 015 m ) and the bacterial debris are partially removed by rubbing gently with cotton wool for cleaning . the replicas on membranes are then treated with proteinase k ( boehringer mannheim gmbh ) at a concentration of 100 μg / ml in a solution of the following composition : tris - hcl 10 mm ph 8 , edta 10 mm , nacl 50 mm and sds 0 . 1 %, at a rate of 20 ml per membrane . the mixture is incubated for 30 min at 37 ° c ., with shaking . the replicas on membranes are reimmersed in a 2 × ssc solution in order to remove definitively all traces of bacterial debris . finally , they are dried for a few minutes on filter paper and then for 30 min under vacuum at + 80 ° c . for each dish , this gives two replicas on membranes , hereafter called replica 1 and replica 2 . the single - cell line u937 atcc 1593 is cultivated in rpmi medium complemented with 10 % of fetal calf serum ( gibco brl -- ref . 013 - 06290h ), to which 10 units of penicillin and 10 μg of streptomycin have been added per ml and to which l - glutamine has been added to a final concentration of 2 mm . for activation of these cells , they are placed in rpmi medium to which penicillin , streptomycin , l - glutamine and 20 ng / ml of phorbol 2 - myristate - 3 - acetate ( pma ) ( sigma -- ref . p8139 ) have been added , for 24 h . the cells activated in this way are scraped and centrifuged . the cell residue obtained is called cell residue u937p . half the cells are additionally induced with cycloheximide ( 10 μg / ml ) during the last two hours of culture . this inhibitor of protein synthesis makes the unstable messenger rnas ( including the cytokinins ) more stable ( cf . t . lindsten et al ., 1989 , science , 244 , 339 - 343 ). the cells activated in this way are scraped and centrifuged . the cell residue obtained is called cell residue u937pc . starting from cell residues u937p and u937pc , the rna is extracted and the poly a + fraction is purified as described in section 1 - 2 ) a ) and b ). this gives two rna - poly a + fractions , called poly a - 1 fraction and poly a + 2 fraction respectively . the radiolabeled cdna probes , called probe 1 and probe 2 respectively , are synthesized from the two rna - poly a + fractions prepared above , in the manner described below . 1 μg of rna - poly a + is hybridized with 200 ng of oligo dt 12 - 18 ( pharmacia ) in 2 to 3 μl of a buffer of the following composition : tris - hcl ph 7 . 5 50 mm and edta 1 mm , by incubation for 2 min at 65 ° c . and cooling to room temperature . the radiolabeled cdna is synthesized in a reaction volume of 10 μl in a buffer of the following composition : tris - hcl 50 mm ph 8 . 3 , mgcl 2 5 mm and dithiothreitol 10 mm , containing 50 μm datp , dgtp and dttp , 10 μm dctp and 150 μci of dctp α 32p ( 3000 ci / mmol , amersham ) and 40 units of rnasin ( rnase inhibitor -- genofit ). the reaction is carried out at 46 ° c . for 30 min in the presence of 10 to 20 units of reverse transcriptase ( genofit ). this synthesis is followed by alkaline hydrolysis of the rna with a 0 . 3 m solution of naoh in a final volume of 20 μl for 30 min at 65 ° c . the mixture is neutralized by the addition of 3 m acetic acid . the volume is adjusted to 50 μl with te medium . extraction is carried out with the same volume of phenol , this being followed by a second extraction with the same volume of a chloroform / isoamyl alcohol mixture ( in the respective proportions 24 / 1 ). the dctp α 32p not incorporated during the synthesis of the cdna strand is removed by exclusion chromatography on a column of polyacrylamide p10 ( biogel - 200 - 400 mesh -- biorad ). the amount of cdna is 60 to 100 ng with a specific activity of 1 × 10 9 dpm / μg . the replicas on membranes are prehybridized for 2 h at 42 ° c . in a buffer of the following composition : 50 % formamide , 6 × ssc , 5 × denhardt &# 39 ; s solution , 0 . 1 % sds and 100 μg / ml of sonicated salmon sperm dna , added after denaturation for 10 min at 100 ° c . the replicas on membranes are hybridized for two days : replica 1 with probe 1 and replica 2 with probe 2 , these probes being used at a concentration of 4 ng / ml in the above buffer . the 5 × denhardt &# 39 ; s solution ( cf . sambrook , op . cit .) has the following composition : ficoll ® ( type 400 -- pharmacia ) 1 g / l , polyvinylpyrrolidone 1 g / l and bovine serum albumin ( bsa ) 1 g / l . the prehybridization and hybridization are effected in tubes in a hybridizing oven ( hybaid ) with 25 ml and 10 ml of buffer , respectively , per membrane . the replicas on membranes are then successively washed several times for 15 min at 20 ° c . in a buffer of the following composition : 2 × ssc and 0 . 1 % sds , and then twice for 15 min in a solution of the following composition : 0 . 1 × ssc and 0 . 1 % sds , at 55 ° c ., dried on whatman 3mm paper and autoradiographed on kodak xar5 films . 5 ) hybridization with a mixture of oligonucleotides corresponding to the majority of the known cytokinins to identify the clones which contain the dnas complementary to the messenger rnas of the known cytokinins , another series of replicas on membranes , prepared as described above , is hybridized with a mixture -- called mixture c -- of 28 oligonucleotides each containing 20 nucleotides , corresponding to the dnas complementary to the following cytokinins : interleukin - 1α ( furutani y . et al ., 1985 , nucl . ac . res ., 13 , 5869 - 5882 ), interleukin - 1β ( auron p . et al ., 1984 , proc . natl . acad . sci . u . s . a ., 81 , 7907 - 7911 ), interleukin - 2 ( degrave w . et al ., 1983 , embo j ., 2 , 3249 - 3253 ), interleukin - 3 ( yang y . c . et al ., 1986 , 47 , 3 - 10 ), interleukin - 4 ( yokoto t . et al ., 1986 , proc . ntl . acad . sci ., 83 , 5894 - 5898 ), interleukin - 5 ( hirano t . et al ., 1986 , nature , 324 , 73 - 75 ), interleukin - 6 ( may l . et al ., 1986 , proc . natl . acad . sci . u . s . a ., 83 , 8957 - 8961 ), interleukin - 7 ( namen a . et al ., 1988 , nature , 333 , 571 - 573 ), interleukin - 8 ( matsushima k . et al ., 1988 , j . exp . med ., 167 , 1883 - 1893 ), interleukin - 9 ( yang y . c . et al ., 1989 , blood , 74 , 1880 - 1884 ), tnfα ( pennica d . et al ., 1984 , nature , 312 , 724 - 729 ), tnfβ ( gray p . et al ., 1984 , nature , 312 , 721 - 724 ), g - csf ( nagata s . et al ., 1986 , 319 , 415 - 418 ), m - csf ( kawasaki e . et al ., 1985 , science , 230 , 291 - 296 ), gm - csf ( wong g . et al ., 1985 , science , 228 , 810 - 815 ), lif ( grough n . et al ., 1988 , proc . natl . acad . sci . u . s . a ., 85 , 2623 - 2627 ), interferon α ( goeddel d . et al ., 1981 , nature , 290 , 20 - 26 ), interferon β1 ( taniguchi t . et al ., 1980 , gene , 10 , 11 - 15 ), interferon γ ( gray p . et al ., 1982 , nature , 295 , 503 - 508 ), tgfα ( derynck r . et al ., 1984 , cell , 38 , 287 - 297 ), tgfβ1 ( derynck r . et al ., 1985 , nature , 316 , 701 - 705 ), bfgf ( prats h . et al ., 1989 , proc . natl . acad . sci . u . s . a ., 86 , 1836 - 1840 ), erythropoietin ( jacobs k . et al ., 1985 , nature , 313 , 806 - 810 ), bcgf ( sharma s . et al ., 1987 , science , 235 , 1489 - 1492 ), mif ( weiser w . et al ., 1989 , proc . natl . acad . sci . u . s . a ., 86 , 7522 - 7526 ), mcp - 1 ( yoshimura t . et al ., febs lett ., 244 , 487 - 493 ), oncostatin - m ( malik n . et al ., 1989 , mol . cell . biol ., 9 , 2847 - 2853 ) and edf ( murata m . et al ., 1988 , proc . natl . acad . sci . u . s . a ., 85 , 2434 - 2438 ). these oligonucleotides , produced using a biosearch 8700 dna synthesizer , are coupled with horseradish peroxidase ec 1 . 11 . 17 ( boehringer mannheim -- ref . 814 - 407 ) according to the following protocol : the oligonucleotides are reacted on the synthesis column with carbonyldiimidazole ( aldrich -- 11 , 553 - 3 ) and 1 , 6 - diaminohexane ( aldrich -- h1 . 169 - 6 ) according to the method of wachter et al ., 1986 , nucl . ac . res ., 14 , 7985 - 7994 . after deprotection of the bases and cleavage of the support by ammoniacal treatment , the oligonucleotides are purified on an ion exchange resin ( quiagen -- diagen - 500051 ), the ammonium counterion being changed to the lithium ion . the 5 &# 39 ;- aminooligonucleotides are coupled with horseradish peroxidase ( boehringer mannheim -- 814407 ) according to the method of m . urdea et al ., nucl . ac . res ., 1988 , 16 , 4937 - 4956 . the mixture of oligonucleotides hybridizes with about 10 % of the clones in the library . the clones which give a stronger autoradiographic signal with probe 2 than with probe 1 , and which do not hybridize with mixture c , were partially sequenced as described in section 4 below . one of these clones , called clone a in french patent application 90 14 961 and designated by clone nc28 in the present patent application , was retained . clone nc28 contains vector pse1 , which carries a cdna between the apai and bamhi sites , hereafter called nc28 cdna . vector pse1 , which contains the origin of replication of phage f1 , makes it possible to produce single - stranded dna by culture of clone nc28 in the presence of bacteriophage m13k07 ( pharmacia -- ref . 27 - 1524 ) in the following manner : clone nc28 is cultivated in a 15 ml tube , with shaking , at 37 ° c ., in 2 ml of 2 × yt medium of the following composition : bactotryptone 16 g / l , yeast extract 10 g / l and nacl 5 g / l ( described in sambrook et al ., op . cit . ), complemented with 0 . 001 % of thiamine and 100 μg / ml of ampicillin , to an optical density of about 0 . 60 at 660 nm . 100 μl of this culture are infected with bacteriophage m13k07 ( pharmacia -- ref . 27 - 1524 ) at a multiplicity of infection of the order of 10 , in a 15 ml tube . the culture is shaken at 37 ° c . after 1 h , 2 ml of medium are added . the culture is then incubated for about 16 h at 37 ° c ., with shaking . 1 . 5 ml of the culture are centrifuged in a microtube at 15 , 000 g for 2 min . 1 ml of supernatant is transferred to a microtube and 250 μl of a 20 % solution of polyethylene glycol ( of molecular weight 6000 ), containing 2 . 5 m nacl , are added . the mixture is incubated for 5 min at 4 ° c . to facilitate precipitation of the phage , and then centrifuged for 5 min at 15 , 000 g . the supernatant is removed and the residue of phage is resuspended in 500 μl of a buffer of the following composition : tris - hcl 10 mm ph 8 and edta 1 mm . the suspension is extracted once with phenol saturated with tris - hcl 100 mm ph 8 , and then twice with chloroform . the preparation is then precipitated by the addition of 1 / 10 volume of a solution of sodium acetate 3 m ph 4 . 8 and 2 . 5 volumes of ethanol . precipitation is effected at - 20 ° c . for a minimum of 20 min . the dna is centrifuged for 10 min at 15 , 000 g and the residue is washed with a 70 % solution of ethanol and then resuspended in 30 μl of a buffer of the following composition : tris - hcl 10 mm ph 8 and edta 1 mm . the sequencing reactions are carried out with the aid of a united states biochemical sequencing kit ( ref . 70770 ), which uses the method of sanger et al ., proc . ntl . acad . sci . u . s . a ., 1977 , 14 , 5463 - 5467 . the primers used are oligonucleotides of 18 nucleotides , which are complementary either to vector pse1 in the region immediately at the 5 &# 39 ; end of nc28 cdna , or to the sequence of nc28 cdna . the following description will be understood more clearly with the aid of fig2 and 4 . fig2 shows the nucleotide sequence of nc28 cdna ( seq id no : 15 ) and , underneath , the translated amino acid sequence ( seq id no : 16 ), the three met capable of initiating translation being underlined , the n - glycosylation site being underlined with a broken line and the probable cleavage site of the signal peptide being indicated by a vertical arrow . fig3 and fig4 respectively show the maximum homology alignment , according to the method of needleman and wunsch , 1970 , j . mol . biol ., 48 , 443 - 453 , of the amino acid sequence translated from nc28 cdna ( upper line , seq id no : 16 ) and of the amino acid sequence translated from the cdna of the cytokinin mcp - 1 ( lower line , seq id no : 24 ), and the alignment , according to this method , of nc28 cdna ( upper line , bases 1 - 800 of seq id no : 15 ) and of the cdna of the cytokinin mcp - 1 ( lower line , seq id no : 25 ). ( 1 ) ( seq id no : 15 ) nc28 cdna contains 804 nucleotides and terminates with a poly a sequence . ( 2 ) this number of nucleotides is in agreement with the size of the corresponding messenger rna ( about 0 . 8 kb ), measured by electrophoresis on 1 % agarose gel in the presence of formaldehyde ( sambrook , op . cit . ), followed by transfer to a nylon membrane ( hybond n +-- amersham ) and hybridization according to the protocol described below . this membrane is hybridized with a probe radiolabeled with 32 p - dctp ( amersham ), produced from nc28 cdna by partial cleavage of the latter with dnase i , followed by polymerization with the aid of the enzyme dna polymerase i ( a technique known as nick translation ), as described by sambrook et al ., op . cit . the hybridization takes place at 42 ° c . for 16 h in an aqueous medium containing 50 % of formamide , 1 m nacl , a 5 × denhardt &# 39 ; s solution and 0 . 1 % of sds . the membranes are washed several times at room temperature with a 2 × ssc solution containing 0 . 1 % of sds , and then washed twice at 50 ° c . for 15 min with a 0 . 1 × ssc solution containing 0 . 1 % of sds . the 5 × denhardt &# 39 ; s solution has the following composition : ficoll ( type 400 -- pharmacia ) 1 g / l , polyvinylpyrrolidone 1 g / l and bsa 1 g / l . the 1 × ssc solution contains 0 . 15 m nacl and 0 . 015 m sodium citrate . ( 3 ) in position 787 - 792 , the sequence cataaa , which resembles the consensus sequence aataaa described by m . birnstiel et al ., 1985 , cell , 41 , 349 , is probably a polyadenylation signal . in position 534 - 554 , of seq id no : 15 a region rich in a and t -- ttattaatattttaatttaat -- contains the instability consensus pattern attta described by g . shaw et al ., 1986 , cell , 46 , 659 - 667 . the majority of the known cytokinins possess such a region rich in a and t , which contains this instability consensus pattern . ( 4 ) the dna sequence contains an open reading frame for the translation of a protein from the atg in position 41 - 43 to the tga in position 368 - 370 of seq id no : 15 , which corresponds to a translation stop codon . in this reading frame , there are three atg codons in positions 41 - 43 , 53 - 55 and 71 - 73 of seq id no : 15 , capable of initiating translation . among these , the nucleotide environment of the atg in positions 71 - 73 is the one most similar to the consensus sequence described by kozak m ., 1978 , cell , 15 , 1109 - 1123 , for initiating translation in eucaryotic cells . ( 5 ) a signal peptide search software , hereafter called ps software , has been developed by the applicant following the method and information described by von heijne , 1986 , nucl . ac . res ., 14 , 483 - 490 . this software anticipates , in this reading frame , a hydrophobic region resembling a signal peptide and a probable protein cleavage site in position 139 - 140 ( between ala and gln ). the anticipated signal peptide is between one of the three met capable of initiating translation , and this cleavage site . the mature protein ( translated protein cleaved from its signal peptide ) therefore comprises 76 amino acids ( cf . fig2 ). ( 6 ) the amino acid sequence of the protein translated from nc28 cdna ( seq id no : 16 ) and the sequence of nc28 cdna ( seq id no : 15 ) were respectively compared with the sequence of the protein translated from the cdna of the cytokinin mcp - 1 and with the sequence of the cdna of the cytokinin mcp - 1 using an appropriate software , namely the uwgcg software from the university of wisconsin : devereux et al ., 1984 , nucl . ac . res ., 12 , 8711 - 8721 -- option gap : optimal sequence alignment according to the method of needleman and wunsch , 1970 , j . mol . biol ., 48 , 443 - 453 . this comparison showed about 74 % identity between the amino acid sequence of the protein translated from nc28 cdna and the sequence of the cytokinin mcp - 1 ( 73 out of the 99 amino acids were identical ) and about 79 % identity between the part of nc28 cdna coding for the translated protein and the cdna of the cytokinin mcp - 1 ( 235 out of the 297 nucleotides were identical ). the cleavage site predicted by the ps software , in position 139 - 140 ( between ala and gln ), corresponds to that found experimentally for the cytokinin mcp - 1 by e . robinson et al ., 1989 , proc . ntl . acad . sci . u . s . a ., 86 , 1850 - 1854 . the atg in position 71 - 73 of nc28 cdna corresponds to the translation initiation atg of the cytokinin mcp - 1 . the homology between the amino acid sequence of the protein translated from nc28 cdna ( seq id no : 16 ) and the sequence of the cytokinin mcp - 1 indicates that the protein translated from nc28 cdna is a secreted protein of the cytokinin type . analysis of the secretion in cos cells of the protein coded by nc28 cdna cos cells are monkey kidney cells expressing sv40 t - antigen ( gluzman y ., cell , 23 , 1981 , 175 - 182 ). these cells , which permit the replication of vectors containing the origin of replication of sv40 dna ( the case of vector pse1 ), constitute preferred hosts for studying the expression of genes in animal cells . 1 ) transfection of cos cells and transitory expression of the protein coded by nc28 cdna 5 × 10 5 cos cells are inoculated in a petri dish of diameter 6 cm ( corning ) in 5 ml of dulbecco &# 39 ; s modified eagle &# 39 ; s medium ( gibco , ref . 041 - 01965 ), hereafter called dmem , which contains 0 . 6 g / l of glutamine and 3 . 7 g / l of nahco , and is complemented with fetal calf serum ( gibco ) at a rate of 5 %. after culture for about 16 h at 37 ° c . in an atmosphere containing 5 % of carbon dioxide , the culture medium is sucked off and the cells are washed with 3 ml of pbs ( phosphate buffered saline from gibco ). the following mixture is then added : 1000 μl of ( dmem + 10 % fetal calf serum ( gibco )), 110 μl of diethylaminoethyldextran of average molecular weight 500 , 000 ( pharmacia ), at a concentration of 2 mg / ml , 1 . 1 μl of chloroquine 100 mm ( sigma ) and 6 μg of plasmid dna of clone nc28 , prepared by the technique of alkaline lysis followed by purification of the plasmid dna on a cesium chloride gradient ( sambrook et al ., op . cit .). after incubation for 5 h at 37 ° c . in an atmosphere containing 5 % of carbon dioxide , the mixture is withdrawn from the cells . 2 ml of pbs containing 10 % of dimethyl sulfoxide ( spectroscopic grade , merck ) are then added . after incubation for 1 min at room temperature , the mixture is withdrawn and the cells are washed twice with pbs and incubated in dmem containing 2 % of fetal calf serum . incubation is continued for 40 h at 37 ° c . under an atmosphere containing 5 % of carbon dioxide . also , control cos cells were prepared by carrying out the above - described operations with the dna of plasmid pse1 . the operations described below are all performed with cos cells transfected by the plasmid dna of clone nc28 and with control cos cells . the culture medium is sucked off and the cells are washed twice with 3 ml of pbs . 5 ml of mem ( eagle &# 39 ; s minimum essential medium ) without methionine ( gibco -- ref . 041 - 01900h ), complemented with 3 g / ml of glucose and 4 mm glutamine , are added . incubation is carried out for 2 h at 37 ° c . the culture medium is removed and a further 2 ml of the same medium , to which 200 μmci of methionine 35s ( ref . sj1015 , amersham ) have been added , are added to the cells . incubation is carried out for 6 h at 37 ° c . the culture medium is removed and centrifuged for 5 min to eliminate the cell debris and suspended cells , and the supernatant is retained . the adhesive cells are rinsed twice with pbs , scraped with a rubber scraper and centrifuged . 3 ) analysis of the radiolabeled proteins of the transfected cos cells by polyacrylamide gel electrophoresis 1 ml of the supernatant of the transfected cos cells and 9 ml of acetone are precipitated at - 20 ° c . the mixture is centrifuged and the protein residues are recovered . they are taken up in a buffer of following composition : tris 0 . 125 m ph 6 . 8 , sds 4 % and glycerol 20 %. an aliquot of the resulting suspension , corresponding to a radioactivity of 200 , 000 cpm , is analyzed by electrophoresis on a 15 % polyacrylamide gel in the presence of sds according to the technique described by u . k . laemmli , anal . biochem ., 1977 , 78 , 459 . the gel is dried under vacuum . the radiolabeled proteins are developed by autoradiography . the autoradiograph shows the presence of four extra bands for the cells transfected by the plasmid dna of clone nc28 , compared with the control cells : two high - intensity bands corresponding to apparent molecular weights of 9 ± 2 and 16 ± 2 kda and two low - intensity bands corresponding to apparent molecular weights of 11 ± 2 and 17 ± 2 kda ( the latter band is diffuse ). the molecular weight calculated for the mature protein of 76 amino acids is 8956 da , i . e . similar to the apparent molecular weight corresponding to the first of these bands . the different bands observed , or some of them , may correspond to various degrees of glycosylation of the protein of the invention . the latter ( cf . fig2 ) in fact has an asparagine residue capable of being n - glycosylated ( underlined with a broken line in fig2 and corresponding to the consensus sequence described by donner et al ., j . cell . biol ., 1987 , 105 , 2665 ) and several serine and threonine residues capable of being o - glycosylated . 4 ) demonstration of the probable n - glycosylation of the forms with apparent molecular weights of 16 ± 2 and 17 ± 2 kda the proteins are labeled as in 2 ) above , but in the presence of 10 mg / ml of tunicamycin ( sigma -- ref . t7765 ), which is a protein n - glycosylation inhibitor . the analysis of the proteins on polyacrylamide gel is performed as in 3 ). the autoradiograph shows the presence of two extra bands for the cells transfected by the plasmid dna of clone nc28 , compared with the control cells : one high - intensity band corresponding to an apparent molecular weight of 9 ± 2 kda and one low - intensity band corresponding to an apparent molecular weight of 11 ± 2 kda . these results show that the two forms of the recombinant protein observed in 3 ), corresponding to molecular weights of 16 ± 2 and 17 ± 2 kda , are n - glycosylated . 4 × 10 7 cos cells are inoculated in a cylindrical culture flask , usually called a roller , with a surface area of 850 cm 2 , in 150 ml of dulbecco &# 39 ; s modified eagle &# 39 ; s medium ( gibco , ref . 041 - 01965 ), hereafter called dmem , which contains 0 . 6 g / l of glutamine and 3 . 7 g / l of nahco 3 and is complemented with fetal calf serum ( gibco ) at a rate of 5 % and then buffered with carbon dioxide . after culture for about 16 h at 37 ° c . with a speed of rotation of about 0 . 2 rpm , the culture medium is sucked off and the cells are washed with pbs ( phosphate buffered saline from gibco ). the following mixture is then added : 36 ml of ( dmem + 10 % fetal calf serum ( gibco )), 4 ml of diethylaminoethyl - dextran of average molecular weight 500 , 000 ( pharmacia ), at a concentration of 2 mg / ml , 40 μl of chloroquine 100 mm ( sigma ) and 128 μg of the plasmid dna of clone nc28 , prepared by the technique of alkaline lysis followed by purification of the plasmid dna on a cesium chloride gradient ( sambrook et al ., op . cit .). after incubation for 5 h at 37 ° c . in an atmosphere containing 5 % of carbon dioxide , the mixture is withdrawn from the cells . 35 ml of pbs containing 7 % of dimethyl sulfoxide ( spectroscopic grade , merck ) are then added . after rotation for 1 min 30 s at room temperature , the mixture is withdrawn and the cells are washed twice with pbs and incubated for 5 days at 37 ° c ., with rotation , in dmem without phenol red . the supernatant , which has a volume of about 130 ml , is removed . the recombinant protein was isolated and purified from the supernatant obtained above , with the following successive steps : ion exchange chromatography on a deae - sepharose column ( pharmacia ) equilibrated beforehand with a solution of tris - hcl 50 mm ph 8 . 0 . under these operating conditions , the protein does not bind to the gel . affinity chromatography on a column of heparin sepharose ( pharmacia ) equilibrated beforehand with a solution of tris - hcl 50 mm ph 8 , using a linear gradient of 0 to 1 m nacl in a solution of tris - hcl 50 mm ph 8 . 0 as the eluent . dialysis of the fractions containing the recombinant protein , whose degree of purity , determined by electrophoretic analysis on polyacrylamide gel in the presence of sds and developing with silver nitrate , is more than 90 %, either against a solution of pbs for the sample subjected to the test for chemotaxis described in section 11 , or against a solution , called solution 1 , of mops buffer 20 mm ph 6 . 4 , containing 0 . 1 m nacl , for the chromatography step below . cation exchange chromatography of these fractions on a mono s ® hr 5 / 5 column ( pharmacia ) equilibrated beforehand with solution 1 , using a linear gradient of 0 . 1 to 0 . 4 m nacl in solution 1 as the eluent ( for 60 min ) and with detection at 280 nm . the recombinant protein is present in the fractions corresponding to two peaks , called fraction 1 and fraction 2 , which , on electrophoretic analysis in the presence of sds , respectively give a majority band with an apparent molecular weight of 9 ± 2 kda and a minority band with an apparent molecular weight of 11 ± 2 kda in one case , and a majority band with an apparent molecular weight of 16 ± 2 kda and a series of weak bands with apparent molecular weights of between ( 16 and 18 )± 2 kda in the other case . analysis of each of these two fractions by polyacrylamide gel electrophoresis in the presence of sds and developing with silver nitrate does not reveal bands other than the forms of protein nc28 described above , showing that the recombinant protein has a degree of purity of at least 95 % in each of the fractions . 3 ) analysis of the amino - terminal sequence of each of fractions 1 and 2 for each of fractions 1 and 2 , the amino - terminal sequence was analyzed using an applied biosystem model 470a sequencer coupled with an applied biosystem model 120a analyzer of phenylthiohydantoic derivatives . the purified protein ( 200 pmol , checked by amino acid analysis ) was deposited on the sequencer in the presence of 20 pmol of the control protein β - lactoglobulin . no amino - terminal sequence corresponding to the amino acid sequence coded by nc28 cdna was detected ( by contrast , the amino - terminal sequence of the control protein was detected , indicating that the sequencer was working ). there is therefore probably amino - terminal blocking of each of the different forms of the recombinant protein . fractions 1 and 2 were digested with the 3 enzymes n - glycanase , neuraminidase and o - glycanase ( genzyme ) following the protocol described in the data sheet supplied with these enzymes . the products of these enzymatic digestions were analyzed by electrophoresis in the presence of sds according to the technique of laemmli u . k ., 1977 , anal . biochem ., 78 , 459 . the results are as follows : the majority band with an apparent molecular weight of 9 ± 2 kda is not modified in the presence of n - glycanase , neuraminidase or o - glycanase . the minority band with an apparent molecular weight of 11 ± 2 kda is not modified by n - glycanase but is modified by neuraminidase to give a band with an apparent molecular weight of 10 ± 2 kda , this band itself being modified by o - glycanase to give a band identical to the majority band with an apparent molecular weight of 9 ± 2 kda . the majority band with an apparent molecular weight of 16 ± 2 kda is not modified by neuraminidase or o - glycanase but , after the action of n - glycanase , it is identical to the majority band with an apparent molecular weight of 9 ± 2 kda . the bands with apparent molecular weights of between ( 16 and 18 )± 2 kda disappear under the action of each of the three enzymes . these experiments show that the majority form with an apparent molecular weight of 9 ± 2 kda is a non - glycosylated form of protein nc28 , the minority form with an apparent molecular weight of 11 ± 2 kda is an o - glycosylated form of protein nc28 containing 1 or more sialic acids , and the majority form with an apparent molecular weight of 16 ± 2 kda is an n - glycosylated form of protein nc28 . the minority forms with apparent molecular weights of between 16 and 18 kda probably represent a complex mixture of n - and o - glycosylated forms . protein nc28 is the first known member of the family of the human sis cytokinins which is n - glycosylated ( a . minty , 1991 , medecine sciences , 7 , 578 ). the cytokinin mcp - 1 exists in an o - glycosylated form but not in an n - glycosylated form ( jiang et al ., 1990 , j . biol . chem ., 30 , 18318 ). construction of an expression vector for nc28 cdna in yeast : plasmid pemr617 and transformation of a yeast strain using this plasmid plasmid pemr583 ( described in european patent application 435776 ) was subjected to complete digestion with the enzymes hindiii and bamhi . the large fragment ( hereafter called fragment a ), comprising the 2 micron origin of replication and stb locus , the leu2d gene , the ampicillin resistance gene , the origin of pbr322 , the terminator of the pgk gene , the ura3 gene , the artificial promoter and the start of the prepro region of pheromone alpha , was purified . the hindiii - bamhi fragment ( hereafter called fragment b ), comprising the end of the prepro region of pheromone alpha and the cdna coding for the mature protein , flanked by the bamhi restriction site at the 3 &# 39 ; end , was obtained by amplification using the pcr technique starting from plasmid pse1 - nc28 . the sequence of this fragment is detailed in fig5 . fragments a and b were ligated to give plasmid pemr617 . the polymerase chain reaction ( pcr ) technique is a method well known to those skilled in the art , which makes it possible simultaneously to copy the two strands of a previously denatured dna sequence using two oligonucleotides as primers ( cf . especially the work by h . a . erlich : &# 34 ; pcr technology : principles and applications for dna amplification &# 34 ; published in 1989 by macmillan publishers ltd , united kingdom , and the work by m . a . innis et al . : &# 34 ; pcr protocols &# 34 ; published in 1990 by academic press inc ., san diego , calif . 92101 , u . s . a .). the principle of this technique is summarized below . the pcr technique is based on the repetition of three steps , which makes it possible , after between 10 and 30 cycles , to obtain hundreds of thousands of copies of the original template , using a dna polymerase of thermus aquaticus , usually referred to as taq poly - merase . the three steps are as follows : the double - stranded dna is denatured to single - stranded dna by incubation at high temperature ( from 92 ° c . to 96 ° c .) for approximately 2 min . these primers are a pair of synthetic oligo - nucleotides which hybridize with the ends of the region to be amplified . the two primers hybridize with the opposing strands . the primers are added in excess so as to favor the formation of the primer - template complex . the step in which the taq polymerase extends the primer - template complex from the 5 &# 39 ; end to the 3 &# 39 ; end is carried out at 72 ° c . in the pcr technique , the product of interest appears in the third cycle and is then amplified significantly . in the course of the cycles , the amplification product rapidly becomes the template with which the primers hybridize . the first oligonucleotide , referred to as primer 1 , which has the following sequence ( seq id no : 21 ): atcga agc ttg gat aaa aga cag cca gtt ggg att aat ac ser leu asp lys arg gln pro val gly ile asn region 1 region 2 possesses two distinct regions : region 1 , which contains the end of the prepro region of pheromone a modified relative to the natural sequence described by kurjan et al ., cell , 1982 , 30 , 933 - 943 , by a silent mutation which makes it possible to introduce a hindiii site just before the coding part of region 1 ( fifth nucleotide of region 1 ), and region 2 , a region which is intended to hybridize with the coding region corresponding to the start of the mature protein of 76 amino acids ( cf . section 4 ) of the non - coding strand of that part of plasmid pse1 - nc28 which carries nc28 cdna . the second oligonucleotide , referred to as primer 2 , which has the following sequence ( seq id no : 23 ): also consists of two distinct regions : region 1 , which carries a bamhi site on the fifth nucleotide , and region 2 , which carries a nucleotide sequence corresponding to the last codons of the coding part of nc28 cdna and to the stop codon , with a mutation which is intended to eliminate the hindiii site ( silent mutation of codon aag to aaa ). this region is intended to hybridize with the coding strand of that part of plasmid pse1 - nc28 which carries nc28 cdna . c ) preparation of the hindiii - bamhi amplified fragment representing the end of the prepro region of pheromone α and the cdna coding for mature protein nc28 the template used is plasmid pse1 - nc28 , which carries the cdna coding for protein nc28 . 100 ng of plasmid pse1 - nc28 , 100 ng of primer 1 , 100 ng of primer 2 and 5 μl of 10 - fold concentrated reaction mixture ( final amount : 67 mm tris - hcl ph 8 . 8 , 16 . 6 mm ( nh 4 ) 2 so 4 , 1 mm β - mercaptoethanol , 6 . 7 mm edta , 0 . 15 % triton × 100 , 2 mm mgcl 2 , 0 . 2 mm dntp , 200 ng of gelatin ) are placed in a tube and the volume of the mixture is then made up to 50 ml by the addition of water . 0 . 5 μl , i . e . 2 . 5 units , of taq polymerase ( boehringer mannheim ref . 1146 - 173 ) is added . the mixture is then covered with paraffin to prevent evaporation of the aqueous solution . amplification takes place over 15 reaction cycles , the steps of one cycle being as follows : after the 15 cycles , the enzymatic reaction is stopped by the addition of 20 mm edta . the dna fragment amplified in this way , which has the expected size of about 250 bp , is then isolated and purified on 1 % agarose gel , dialyzed by chromatography on a column of p10 polyacrylamide gel ( pharmacia ) and then hydrolyzed totally and simultaneously with the enzymes hindiii and bamhi by the customary techniques well known to those skilled in the art ( sambrook et al ., op . cit .) so as to form the hindiii and bamhi sticky ends . after hydrolysis , the fragment is purified on a plo column . the sequence of the fragment b obtained is shown in fig5 ( seq id no : 17 ). in its part coding for protein nc28 , it comprises a silent mutation relative to nc28 cdna , indicated by an asterisk in fig5 . 2 ) transformation of the yeast strain emy761 with plasmid pemr617 and expression of protein nc28 by the transformed strain the strain emy761 ( mat alpha , leu2 , ura3 , his3 ) described in european patent 0408461 , which can be obtained by plasmid curing of the strain deposited in the cncm on 27th december 1989 under no . i - 1021 , contains mutations ( leu2 and ura3 ) which are capable of being complemented by the leu2d defective selection marker and ura3 selection marker present in plasmid pemr617 . it was transformed with plasmid pemr617 , with selection for the prototrophy of leucine , using a variant of the transformation technique described by beggs et al . ( beggs et al ., 1978 , nature 275 , 104 - 109 ), which consists in subjecting the yeasts to a protoplastization treatment in the presence of an osmotic stabilizer , namely sorbitol at a concentration of 1 m . a ) 200 ml of liquid ypg medium ( cf . table 1 below ) are inoculated with about 5 × 10 6 cells of a culture in the stationary phase , and the culture inoculated in this way is shaken overnight at 30 ° c . b ) when the culture reaches about 10 7 cells per ml , the cells are centrifuged at 4000 rpm for 5 min and the residue is washed with a 1 m solution of sorbitol . c ) the cells are suspended in 5 ml of 1 m sorbitol solution containing 25 mm edta and 50 mm dithiothreitol , and incubated for 10 min at 30 ° c . d ) the cells are washed once with 10 ml of 1 m sorbitol solution and suspended in 20 ml of sorbitol solution . zymolase ®- 100t ( a preparation marketed by seykagaku kogyo co . ltd ., obtained by partial purification of arthobacter luteus culture supernatant on an affinity column and containing β - 1 , 3 - glucanaselaminaripentahydrolase ) is added to a final concentration of 20 μg / ml and the suspension is incubated at room temperature for about 15 min . e ) the cells are resuspended in 20 ml of a sorbitol - containing medium called ypg sorbitol medium ( cf . table 1 below ) and incubated for 20 min at 30 ° c ., with gentle shaking . f ) the suspension is centrifuged for 3 min at 2500 rpm . g ) the cells are resuspended in 9 ml of a transformation buffer of the following composition : sorbitol 1 m , tris - hcl ph 7 . 5 10 mm and cacl 2 10 mm ). h ) 0 . 1 ml of cells and 5 μl of dna solution ( about 5 mg ) are added and the suspension obtained is left for 10 to 15 min at room temperature . i ) 1 ml of the following solution is added : polyethylene glycol peg 4000 20 %, tris - hcl 10 mm ph 7 . 5 and cacl 2 10 mm . j ) 0 . 1 ml of the suspension obtained in i ) is poured into a tube containing leucine - free solid regeneration medium ( cf . table 1 below ) which has been melted beforehand and kept liquid at about 45 ° c . the suspension is poured into a petri dish containing a solidified layer of 15 ml of leucine - free solid regeneration medium . the transformants start to appear after three days . a transformant called strain emy761 pemr617 was thus obtained . composition and preparation of the principal media used in the protocol for transformation of the yeast strain emy761 mix the ingredients in distilled water . make up to a final volume of 1 l with distilled water . autoclave for 15 min at 120 ° c . use the formulation of the liquid ypg medium and , after autoclaving , add sorbitol to a concentration of 1 m . mix all the ingredients in distilled water . make up to a final volume of 1 l with distilled water . autoclave for 15 min at 120 ° c . after autoclaving , add 200 mg of l - threonine and 100 mg of l - aspartic acid . expression , in an erlenmeyer flask , of protein nc28 by the transformed yeast strain and detection of the protein in the culture medium on polyacrylamide gel in the presence of sds a colony of the strain emy761 pemr617 ( obtained in section 7 ) was cultured in 50 ml of uracil - free liquid medium . this medium contains the following per liter : 6 . 7 g of yeast nitrogen base without amino acids ( from difco ) after one night at 30 ° c ., with shaking , the culture was centrifuged for 10 min and the residue was taken up in 10 ml of sterile water and centrifuged again for 10 min . the expression of protein nc28 was induced by taking up the cells in 50 ml of a medium of the following composition : 6 . 7 g / l of yeast nitrogen base without amino acids ( from difco ) the culture was reincubated at 30 ° c . for 24 h , with shaking . some of the cells cultivated overnight in a medium called uracil - free liquid medium with glucose , the composition of which is specified in table 2 below , were centrifuged to give a non - induced sample . the cells cultivated overnight in a medium called uracil - free liquid medium with ethanol , glycerol and galactose ( table 2 below ) were centrifuged to give an induced sample . the supernatant was collected . 5 ml of 50 % trichloroacetic acid containing 2 mg / ml of deoxycholate were added to 10 ml of supernatant . the mixture was left at a temperature of + 40 ° c . for 30 min and then centrifuged for 30 min . the residue was taken up in about 1 ml of cold acetone (+ 4 ° c .) and centrifuged again for 30 min . after drying , the residue is taken up in about 20 μl of a so - called loading buffer consisting of tris - hcl 0 . 125 m ph 6 . 8 , sds 4 %, bromophenol blue 0 . 002 %, glycerol 20 % and β - mercaptoethanol 10 %, according to the protocol described by laemmli ( op . cit .). the residue is solubilized by boiling for 15 min and then neutralized until the bromophenol blue turns blue . the samples are deposited on a polyacrylamide gel in the presence of sds and subjected to electrophoresis . analysis of the gel ( developing with coomassie blue ) shows the presence of several additional bands for the induced sample compared with the non - induced sample , the two main additional bands corresponding to an apparent molecular weight of 9 ± 2 ( majority form ) and 11 ± 2 kda . the other additional bands observed , with an apparent molecular weight of more than 16 ± 2 kda , which are fairly numerous and diffuse , probably correspond to a variable degree of glycosylation . a band of low intensity is also observed , corresponding to an apparent molecular weight of 8 kda . it is known that the n - glycosylation of a protein with yeast involves a simple n - glycosylation ( core glycosylation ) in the endoplasmic reticulum and an n - hyperglycosylation ( outer - chain glycosylation ) in the golgi apparatus ( r . a . hitzeman et al ., 1990 , &# 34 ; methods in enzymology , no . 185 &# 34 ;, academic press , p . 421 - 440 ). in general , core glycosylation produces a glycoprotein of homogeneous apparent molecular weight ( one band ) and outer - chain glycosylation produces a glycoprotein of heterogeneous apparent molecular weight ( several diffuse bands ). it is also known that certain proteins can be o - glycosylated by yeast ( j . zueco et al ., 1986 , biochemica et biophysica acta , 884 , 93 - 100 ). n - glycosylation can be demonstrated in several ways ( p . oleans et al ., 1991 , methods in enzymology , 194 , 682 - 697 ), one of which consists in observing the decrease in the apparent molecular weight of the protein when it is treated with endoglycosidase h ( endo - b - n - acetylglucosaminidase : e . c . 32 . 1 . 96 ), which specifically cleaves n - bonded carbohydrate chains . o - glyco - sylation can be assumed when the protein is resistant to endoglycosidase h and when its apparent molecular weight decreases after treatment with α - mannosidase ( α - d - mannoside mannohydrolase : e . c . 3 . 2 . 1 . 24 ), as described by biemans et al ., 1991 , dna and cell biology , 10 , 191 - 200 . some of the cells cultivated overnight in uracil - free liquid medium with glucose ( table 2 ) were centrifuged to give a non - induced sample . the cells cultivated overnight in uracil - free liquid medium with ethanol , glycerol and galactose ( table 2 ) were centrifuged to give an induced sample . the supernatant was collected . 5 ml of 50 % trichloroacetic acid containing 2 mg / ml of deoxycholate were added to 10 ml of supernatant . the mixture was left at a temperature of 4 ° c . for 30 min and then centrifuged for 30 min . the residue was taken up in about 1 ml of cold acetone (+ 4 ° c .) and centrifuged again for 30 min . the residue is taken up in 40 μl of a solubilization buffer ( composition : tris - hcl ph 6 . 8 10 mm , β - mercaptoethanol 2 %, sds 1 %). the residue is heated at 100 ° c . for 15 min . 10 μl of a sodium citrate buffer 50 mm ph 5 and 5 μl of endoglycosidase h ( 5 miu -- boehringer ref . 1088726 ) are added to the first 10 μl fraction . the sample is left at 37 ° c . for about 1 night . 20 μl of loading buffer are then added . 10 μl of sodium citrate buffer 50 mm ph 5 and 2 . 5 μl of α - mannosidase ( sigma ref . m7257 ) are added to the second 10 pi fraction . the sample is left at 37 ° c . for about 1 night . 20 μl of loading buffer are then added . 10 μl of sodium citrate buffer 50 mm ph 5 and 5 μl of endoglycosidase h ( boehringer ) are added to the third 10 μl fraction . the sample is left at 37 ° c . for about 1 night . 2 . 5 μl of α - mannosidase ( sigma ) are then added . the sample is left at 37 ° c . overnight . 20 μl of loading buffer are added . 10 μl of loading buffer are added to the fourth 10 μl fraction . the samples are boiled for 10 min and deposited on polyacrylamide gel in the presence of sds and electrophoresis is carried out according to the protocol of laemmli , anal . biochem ., 1977 , 78 , 459 . the proteins contained in the gel are then transferred to a nitrocellulose membrane ( by the technique of h . towbin et al ., 1979 , proc . natl . acad . sci . u . s . a ., 76 , 4350 - 4354 ). immunodetection , performed according to the protocol described in the immuno - blot assay kit from bio - rad ( ref . 170 - 6450 ), involves the following steps : saturation of the nitrocellulose membrane for 30 min with tbs ( tris buffered saline ) containing 3 g / 100 ml of gelatin ; rinsing of the membrane twice for 5 min with a buffer called t . tbs ( tbs containing 0 . 05 % of tween 20 ); bringing of the membrane into contact , for 1 h at room temperature , with the immune serum prepared in section 10 ; rinsing of the membrane twice for 5 min with t . tbs and once for 5 min with tbs ; the antigen - antibody complex is developed by bringing the membrane into contact with a developing buffer containing 4 - chloro - 1 - naphthol in diethylene and hydrogen peroxide ; analysis of the immunoblotting shows the presence of several additional bands for the induced sample not treated with endoglycosidase h compared with the non - induced sample , the two main additional bands corresponding to an apparent molecular weight of 9 ± 2 and 11 ± 2 kda . these two bands are recognized by the immune serum . diffuse bands with an apparent molecular weight of more than 16 ± 2 kda are also detected . in the induced sample , the diffuse bands corresponding to a molecular weight of more than 16 ± 2 kda tend to disappear after treatment with endoglycosidase h in favor of a band with an apparent molecular weight of 16 ± 2 kda which may correspond to the precursor retaining the pro - sequence of the pheromone . in this same treated sample , it is noted that the two main bands with apparent molecular weights of 9 ± 2 and 11 ± 2 kda are still present . in the induced sample , the band corresponding to an apparent molecular weight of 11 ± 2 kda tends to disappear after treatment with α - mannosidase , whereas the band of 9 ± 2 kda increases in intensity under the same conditions . this seems to indicate that the protein corresponding to an apparent molecular weight of 11 ± 2 kda is o - glycosylated . composition and preparation of certain media used to prepare the samples 6 . 7 g of yeast nitrogen base without amino acids ( from difco ) mix all the ingredients in distilled water and make up to a final volume of 1 l with distilled water . autoclave for 10 min at 120 ° c . use the formulation of the uracil - free liquid medium described above , but without glucose . after autoclaving , add 10 ml of ethanol 100 %, 30 g of glycerol and 30 g of galactose . purification of protein nc28 produced in yeast and determination of its amino - terminal sequence 1 ) purification of the majority form of protein nc28 produced by yeast the majority form of the recombinant protein with an apparent molecular weight of 9 ± 2 kda ( cf . section 8 - 2 )- a )) was isolated and purified from the culture medium obtained at the end of section 8 - 1 ), using a protocol comprising the following successive steps : ion exchange chromatography on a deae - sepharose ® column ( pharmacia ) equilibrated beforehand with a solution of tris - hcl 50 mm ph 8 . 0 . under these operating conditions , the protein does not bind to the gel . affinity chromatography on a column of heparin sepharose ® ( pharmacia ) equilibrated beforehand with a solution of tris - hcl 50 mm ph 8 , using a linear gradient of 0 to 1 m nacl in a solution of tris - hcl 50 mm ph 8 . 0 as the eluent . dialysis of the fractions containing the recombinant protein ( determined by electrophoretic analysis on polyacrylamide gel in the presence of sds ) against a solution of pbs . analysis by electrophoresis on polyacrylamide gel in the presence of sds , and developing with silver nitrate , shows the presence of one intense band corresponding to an apparent molecular weight of 9 ± 2 kda and two bands of very low intensity corresponding to apparent molecular weights of 8 ± 2 and 11 ± 2 kda . the purity of the recombinant protein corresponding to these three bands is greater than 90 %. the amino - terminal sequence is determined according to edman &# 39 ; s degradation principle ( kia - ki han et al ., 1977 , biochimie , 59 , 557 ). the first amino - terminal amino acid is coupled with phenyl isothio - cyanate ( pitc ) and then cleaved . the derivative obtained is converted to a stable phenylthiohydantoin / amino acid absorbing at 269 nm . the product of each cycle is analyzed by hplc . the three amino - terminal sequences below are detected in respective proportions of 70 %, 20 % and 10 %: sequence 1 : ( amino acids 1 - 7 of seq id no : 2 ) gln pro val gly ile asn thr sequence 2 : ( amino acids 3 - 7 of seq id no : 2 ) val gly ile asn thr sequence 3 : ( amino acids 19 - 23 of seq id no : 2 ) lys ile pro lys gln sequence 1 is the expected amino - terminal sequence , namely that of the mature protein of 76 amino acids ( cf . fig2 ) described in section 4 , the coding sequence of which is introduced into vector pemr617 described in section 7 . sequences 1 and 2 ( amino acids 1 - 7 and 3 - 7 , respectively , of seq id no : 2 ) are the amino - terminal sequences of the mature protein of 76 amino acids cleaved in its amino - terminal part of 2 and 18 amino acids respectively . several peptides were synthesized , either manually by the so - called tea bag method described by houghten , 1985 , proc . natl . acad . sci . u . s . a ., 82 , 5131 , or by a method using a milligen synthesizer . in the first method , the synthesis support is enclosed in a solvent - resistant permeable envelope ; thus the common synthesis steps ( activations , washes , etc .) can be carried out simultaneously for a large number of peptides . the second method makes it possible to carry out a completely automated synthesis . in both cases , the synthetic chemistry is that commonly used for solid phase peptide synthesis ( merrifield et al ., 1963 , j . am . chem . soc ., 85 , 2149 - 2154 ). in this method , the carboxy - terminal residue of the peptide to be synthesized is attached to an insoluble polymer and different amino acids are then added . the polypeptide chain increases in size in the amino - terminal direction . after the synthesis , the peptide is separated from the support with hydrofluoric acid and recovered in solution . the first method was used to synthesize the peptides corresponding to amino acids 90 - 109 , 94 - 109 and 97 - 109 ( amino acids 57 - 76 , 61 - 76 and 64 - 76 of seq id no 16 , respectively of the translated protein nc28 ( seq id no : 16 ) ( cf . fig2 ), which are called peptide c20 , peptide c16 and peptide c13 respectively . the peptide corresponding to amino acids 48 - 69 ( amino acids 15 - 36 of seq id no 16 ) of the protein translated from nc28 cdna ( seq id no : 16 ), called peptide 48 - 69 , was synthesized automatically . all the peptides were purified by hplc and determination of the amino acid composition and sequencing of the peptide were carried out on the purified products . analysis of the amino acid composition is entirely automated . the amino acid analyzer ( model 420a , applied biosystems ) effects hydrolysis followed by derivatization of the amino acids released . the derivatized amino acids are separated by a brownlee 130a hplc system connected in line with the 420a system . the amino - terminal sequence is determined according to edman &# 39 ; s degradation principle . the first amino - terminal amino acid is coupled with phenyl iso - thiocyanate ( pitc ) and then cleaved . the derivative obtained is converted to a stable phenylthiohydantoin / amino acid absorbing at 254 nm . the product of each cycle is analyzed by hplc . to produce immune sera , peptide 48 - 69 is coupled with a protein carrying the hemocyanin of fisurella ( klh ) by its carboxy - terminal cysteine residue using m - maleimidobenzoyl - n - hydroxysuccinimide ester ( mbs ) as the coupling agent . rabbits ( new zealand , male , about 2 kg ) are immunized with the conjugate peptide 48 - 69 / klh ( amount corresponding to 800 μg of peptide ) ( rabbit no . 43 ) or with 50 μg of protein nc28 ( purified from yeast -- section 9 ) ( rabbit no . 44 ) every two weeks according to the protocol described by vaitukaitis , 1981 , methods in enzymology , 73 , 46 . for the first injection , one volume of antigenic solution is emulsified with one volume of freund &# 39 ; s complete adjuvant ( sigma -- ref . 4258 ). the booster doses ( 3 for rabbit no . 43 and 6 for rabbit no . 44 ) are administered in freund &# 39 ; s incomplete adjuvant ( sigma -- ref . 5506 ). the immune sera obtained are capable of recognizing protein nc28 produced in yeast and in cos cells by immunodetection after electrophoresis on polyacrylamide gel in the presence of sds . demonstration of a chemotactic activity for protein nc28 and the carboxy - terminal peptides thereof most of the erythrocytes are removed from peripheral blood by sedimentation at 37 ° c . for 30 min in a solution containing 0 . 6 % of dextran t500 ( pharmacia -- ref . 17 - 0320 - 01 ) and 0 . 09 % of nacl . the cells are subsequently deposited on top of a layer of ficoll - paque ® ( pharmacia ) and centrifuged at 400 g for 30 min . the peripheral blood mononuclear cells ( pbmnc ) are present at the interface between the ficoll ® and the supernatant , whereas the residual erythrocytes and the poly - nuclear cells ( mainly neutrophils ) are in the cell residue . this residue is resuspended in a solution of nh 4 cl 0 . 8 %, 10 mm hepes and incubated at 37 ° c . for 7 min in order to burst the erythrocytes . the residual cells ( mainly neutrophils ) are centrifuged and washed in hbss ( hanks &# 39 ; balanced salt solution ) buffer ( gibco brl -- ref . 041 - 04020 h ), hereafter referred to as hbss . the principle of the isolation of monocytes has been described by a . boyum , 1983 , scan . j . immunol ., 17 , 429 - 436 . it is summarized below . the method consists in separating the monocytes from the blood using the iodine - containing gradient medium nycodenz ® ( n , n &# 39 ;- bis ( 2 , 3 - dihydroxypropyl )- 5 -[ n -( 2 , 3 - dihydroxypropyl ) acetamido ]- 2 , 4 , 6 - triiodoisophthalamide ). to accentuate the difference in density between the monocytes and lymphocytes , the osmolarity of the solution is increased so that the lymphocytes reject water and become denser . it is possible to use &# 34 ; nycopred ® 1 . 068 &# 34 ; medium , which contains nycodenz , sodium chloride and tricin / naoh at optimal concentrations for the separation of monocytes ( nycomed pharma as , norway -- ref . 223510 ). most of the erythrocytes are removed from peripheral blood by sedimentation at 37 ° c . for 30 min in a solution containing 0 . 6 % of dextran and 0 . 09 % of nacl . the upper phase of the plasma , containing the monocytes , lymphocytes and neutrophils , is removed . to separate the monocytes from the other cells , tubes are prepared as follows : 6 ml of plasma are deposited on a layer of 3 ml of nycopred ® 1 . 068 ( nycomed pharma as , norway -- ref . 223510 ) in a tube of diameter 13 - 14 mm . after centrifugation at 600 g for 15 min , the clarified plasma is removed down to 3 - 4 mm above the interphase and the remainder of the plasma and all the nycopred ® solution are collected down to about 1 cm above the cell residue , whereby the lymphocytes are not removed . the monocyte suspension collected is made up to a volume of 6 - 7 ml with a solution of the following composition : 0 . 9 % nacl , 0 . 13 % edta , 1 % bsa , and then centrifuged for 7 min at 600 g . the monocytes are contaminated with platelets . the latter are removed by centrifugation followed by removal of the supernatant and resuspension with the same solution , these operations being repeated 3 times . the cells are resuspended in rpmi 1640 medium ( gibco ) containing 0 . 5 % of bovine serum albumin ( bsa ). the test used is the one described by w . falk et al ., 1980 , j . imm . meth ., 33 , 239 - 247 . the precise protocol used is explained below : boyden &# 39 ; s chamber modified for the measurement of chemotaxis , marketed by neuroprobe ( ref . ap48 ), is used . the test samples , diluted in hbss for the tests on the neutrophils and in rpmi medium containing 0 . 5 % of bsa for the test on the monocytes , are placed in the wells in the lower plate . a polycarbonate filter ( pore size : 5 mm ; nuclepore -- ref . 155845 ) is laid on said plate with the shiny side down . the upper plate is laid on the filter . the cells ( 50 , 000 per 50 μl of buffer ) are placed in the wells in the upper plate . the chamber is incubated at 37 ° c . in a humidified oven or in a box containing wet cotton , for 1 h in the case of the test on the neutrophils and for 3 h in the case of the test on the monocytes . the filter is withdrawn and the cells which are on the dull side ( cells which have not migrated ) are removed by wiping the filter and scraping it with a rubber scraper , these last two operations being repeated once . the cells which have migrated are stained and fixed using the &# 34 ; diff - quick &# 34 ; kit ( dade -- ref . 130832 ). the number of cells on the shiny side of the filter ( cells which have migrated ) are counted under the microscope . protein nc28 derived from cos cells , purified as described in section 6 . protein nc28 derived from yeast , purified as described in section 9 . cytokinin mcp - 1 , obtained as follows : isolation of a plasmid pse1 carrying the cdna of cytokinin mcp - 1 by screening the library prepared in section 2 using an oligonucleotide corresponding to part of the cdna of cytokinin mcp - 1 , described by yoshimura t . et al ., 1989 , febs lett ., 244 , 487 - 493 , followed by transfection of the cos cells , culture of the transfected cos cells and purification of the cytokinin mcp - 1 , as described for protein nc28 . b ) samples of peptides ## equ1 ## peptide formyl - met - leu - phe , generally called fmlp ( sigma -- ref . f 3506 ) 2 ) results a ) chemotaxis of purified protein nc28 derived from cos cells , and of purified protein nc28 derived from yeast , on monocytes some of the results obtained are illustrated in fig6 a , which shows the number of cells per microscopic field as a function of the concentration expressed in nm for purified protein nc28 derived from yeast , purified protein nc28 derived from cos cells and peptides c13 , c16 , c20 and fmlp , and in fig6 b , which shows the number of cells per microscopic field as a function of the concentration expressed in ng / ml for purified protein nc28 derived from yeast and purified cytokinin mcp - 1 derived from cos cells . fig6 a shows that , after 3 h of incubation , purified protein nc28 derived from yeast and purified protein nc28 derived from cos cells have a chemotactic activity on monocytes which is markedly greater than that of fmlp , a peptide which is known to possess a chemotactic activity on monocytes ( schiffmann e . et al ., j . immunol ., 114 , 1831 ). the carboxy - terminal peptides of protein nc28 also possess this activity . fig6 b shows that the chemotactic activity of protein nc28 on monocytes is of the same order of magnitude as that of protein mcp - 1 , which is known for this activity ( rollins b . j . et al ., 1991 , blood , 78 , 1112 ), and that this activity is found at concentrations of 0 . 1 to 10 ng / ml . b ) chemotaxis of purified protein nc28 derived from yeast , on neutrophils some of the results obtained are illustrated in fig6 c , which shows the number of cells per microscopic field as a function of the concentration expressed in ng / ml for purified protein nc28 derived from yeast , cytokinin il - 8 and peptide fmlp . it is found that protein nc28 has only a weak chemotactic activity on neutrophils ( at high concentrations in excess of 100 ng / ml ), in contrast to cytokinin il - 8 and peptide fmlp , both of which are known to possess this activity ( yoshimura t . et al ., 1987 , proc . natl . acad . sci . u . s . a ., 84 , 9233 , 1 , and schiffman e . et al ., 1975 , j . immunol ., 114 , 1831 ). protein nc28 is therefore a powerful and specific chemoattractant for monocytes . __________________________________________________________________________ # sequence listing - - - - ( 1 ) general information : - - ( iii ) number of sequences : 25 - - - - ( 2 ) information for seq id no : 1 : - - ( i ) sequence characteristics : ( a ) length : 13 amino - # acids ( b ) type : amino acid ( d ) topology : linear - - ( ii ) molecule type : protein - - ( xi ) sequence description : seq - # id no : 1 : - - met lys his leu asp lys lys thr gln thr pr - # o lys leu 1 5 - # 10 - - - - ( 2 ) information for seq id no : 2 : - - ( i ) sequence characteristics : ( a ) length : 63 amino - # acids ( b ) type : amino acid ( d ) topology : linear - - ( ii ) molecule type : protein - - ( xi ) sequence description : seq - # id no : 2 : - - gln pro val gly ile asn thr ser thr thr cy - # s cys tyr arg phe ile 1 5 - # 10 - # 15 - - asn lys lys ile pro lys gln arg leu glu se - # r tyr arg arg thr thr 20 - # 25 - # 30 - - ser ser his cys pro arg glu ala val ile ph - # e lys thr lys leu asp 35 - # 40 - # 45 - - lys glu ile cys ala asp pro thr gln lys tr - # p val gln asp phe50 - # 55 - # 60 - - - - ( 2 ) information for seq id no : 3 : - - ( i ) sequence characteristics : ( a ) length : 61 amino - # acids ( b ) type : amino acid ( d ) topology : linear - - ( ii ) molecule type : protein - - ( xi ) sequence description : seq - # id no : 3 : - - val gly ile asn thr ser thr thr cys cys ty - # r arg phe ile asn lys 1 5 - # 10 - # 15 - - lys ile pro lys gln arg leu glu ser tyr ar - # g arg thr thr ser ser 20 - # 25 - # 30 - - his cys pro arg glu ala val ile phe lys th - # r lys leu asp lys glu 35 - # 40 - # 45 - - ile cys ala asp pro thr gln lys trp val gl - # n asp phe50 - # 55 - # 60 - - - - ( 2 ) information for seq id no : 4 : - - ( i ) sequence characteristics : ( a ) length : 45 amino - # acids ( b ) type : amino acid ( d ) topology : linear - - ( ii ) molecule type : protein - - ( xi ) sequence description : seq - # id no : 4 : - - lys ile pro lys gln arg leu glu ser tyr ar - # g arg thr thr ser ser 1 5 - # 10 - # 15 - - his cys pro arg glu ala val ile phe lys th - # r lys leu asp lys glu 20 - # 25 - # 30 - - ile cys ala asp pro thr gln lys trp val gl - # n asp phe 35 - # 40 - # 45 - - - - ( 2 ) information for seq id no : 5 : - - ( i ) sequence characteristics : ( a ) length : 25 amino - # acids ( b ) type : amino acid ( d ) topology : linear - - ( ii ) molecule type : peptide - - ( xi ) sequence description : seq - # id no : 5 : - - met ala pro ser gly lys ser thr leu leu le - # u leu phe leu leu leu 1 5 - # 10 - # 15 - - cys leu pro ser trp asn ala gly ala 20 - # 25 - - - - ( 2 ) information for seq id no : 6 : - - ( i ) sequence characteristics : ( a ) length : 89 amino - # acids ( b ) type : amino acid ( d ) topology : linear - - ( ii ) molecule type : protein - - ( xi ) sequence description : seq - # id no : 6 : - - met ser ser pro leu lys asn ala leu val th - # r ala met leu ala gly 1 5 - # 10 - # 15 - - gly ala leu ser ser pro thr lys gln his va - # l gly ile pro val asn 20 - # 25 - # 30 - - ala ser pro glu val gly pro gly lys tyr se - # r phe lys gln val arg 35 - # 40 - # 45 - - asn pro asn tyr lys phe asn gly pro leu se - # r val lys lys thr tyr50 - # 55 - # 60 - - leu lys tyr gly val pro ile pro ala trp le - # u glu asp ala val gln 65 - # 70 - # 75 - # 80 - - asn ser thr ser gly leu ala glu arg 85 - - - - ( 2 ) information for seq id no : 7 : - - ( i ) sequence characteristics : ( a ) length : 23 amino - # acids ( b ) type : amino acid ( d ) topology : linear - - ( ii ) molecule type : peptide - - ( xi ) sequence description : seq - # id no : 7 : - - met lys ala ser ala ala leu leu cys leu le - # u leu thr ala ala ala 1 5 - # 10 - # 15 - - phe ser pro gln gly leu ala 20 - - - - ( 2 ) information for seq id no : 8 : - - ( i ) sequence characteristics : ( a ) length : 29 amino - # acids ( b ) type : amino acid ( d ) topology : linear - - ( ii ) molecule type : peptide - - ( xi ) sequence description : seq - # id no : 8 : - - met pro ser pro ser asn met lys ala ser al - # a ala leu leu cys leu 1 5 - # 10 - # 15 - - leu leu thr ala ala ala phe ser pro gln gl - # y leu ala 20 - # 25 - - - - ( 2 ) information for seq id no : 9 : - - ( i ) sequence characteristics : ( a ) length : 33 amino - # acids ( b ) type : amino acid ( d ) topology : linear - - ( ii ) molecule type : peptide - - ( xi ) sequence description : seq - # id no : 9 : - - met trp lys pro met pro ser pro ser asn me - # t lys ala ser ala ala 1 5 - # 10 - # 15 - - leu leu cys leu leu leu thr ala ala ala ph - # e ser pro gln gly leu 20 - # 25 - # 30 - - ala - - - - ( 2 ) information for seq id no : 10 : - - ( i ) sequence characteristics : ( a ) length : 69 base - # pairs ( b ) type : nucleic acid ( c ) strandedness : single ( d ) topology : linear - - ( ii ) molecule type : dna ( genomic ) - - ( xi ) sequence description : seq - # id no : 10 : - - atgaaagcct ctgcagcact tctgtgtctg ctgctcacag cagctgcttt ca -# gcccccag 60 - - gggcttgct - # - #- # 69 - - - - ( 2 ) information for seq id no : 11 : - - ( i ) sequence characteristics : ( a ) length : 87 base - # pairs ( b ) type : nucleic acid ( c ) strandedness : single ( d ) topology : linear - - ( ii ) molecule type : dna ( genomic ) - - ( xi ) sequence description : seq - # id no : 11 : - - atgccctcac cctccaacat gaaagcctct gcagcacttc tgtgtctgct gc -# tcacagca 60 - - gctgctttca gcccccaggg gcttgct - # - # 87 - - - - ( 2 ) information for seq id no : 12 : - - ( i ) sequence characteristics : ( a ) length : 99 base - # pairs ( b ) type : nucleic acid ( c ) strandedness : single ( d ) topology : linear - - ( ii ) molecule type : dna ( genomic ) - - ( xi ) sequence description : seq - # id no : 12 : - - atgtggaagc ccatgccctc accctccaac atgaaagcct ctgcagcact tc -# tgtgtctg 60 - - ctgctcacag cagctgcttt cagcccccag gggcttgct - # - # 99 - - - - ( 2 ) information for seq id no : 13 : - - ( i ) sequence characteristics : ( a ) length : 228 base - # pairs ( b ) type : nucleic acid ( c ) strandedness : single ( d ) topology : linear - - ( ii ) molecule type : dna ( genomic ) - - ( iii ) hypothetical : no - - ( xi ) sequence description : seq - # id no : 13 : - - cagccagttg ggattaatac ttcaactacc tgctgctaca gatttatcaa ta -# agaaaatc 60 - - cctaagcaga ggctggagag ctacagaagg accaccagta gccactgtcc cc -# gggaagct 120 - - gtaatcttca agaccaaact ggacaaggag atctgtgctg accccacaca ga -# agtgggtc 180 - - caggacttta tgaagcacct ggacaagaaa acccaaactc caaagctt - # 228 - - - - ( 2 ) information for seq id no : 14 : - - ( i ) sequence characteristics : ( a ) length : 422 base - # pairs ( b ) type : nucleic acid ( c ) strandedness : double ( d ) topology : linear - - ( ii ) molecule type : dna ( genomic ) - - ( iii ) hypothetical : no - - ( xi ) sequence description : seq - # id no : 14 : - - agctggctcg catctctcct tcacgcgccc gccgccctac ctgaggccgc ca -# tccacgcc 60 - - ggtgagtcgc gttctgccgc ctcccgcctg tggtgcctcc tgaactgcgt cc -# gccgtcta 120 - - ggtaggctcc aagggagccg gacaaaggcc cggtctcgac ctgagctcta aa -# cttaccta 180 - - gactcagccg gctctccacg ctttgcctga ccctgcttgc tcaactctac gt -# ctttgttt 240 - - cgttttctgt tctgcgccgt tacaacttca aggtatgcgc tgggacctgg ca -# ggcggcat 300 - - ctgggacccc taggaagggc ttgggggtcc tcgtgcccaa ggcagggaac at -# agtggtcc 360 - - caggaagggg agcagaggca tcagggtgtc cactttgtct ccgcagctcc tg -# agcctgca 420 - - ga - # - # - # 422 - - - - ( 2 ) information for seq id no : 15 : - - ( i ) sequence characteristics : ( a ) length : 814 base - # pairs ( b ) type : nucleic acid ( c ) strandedness : single ( d ) topology : linear - - ( ii ) molecule type : cdna - - ( iii ) hypothetical : no - - ( ix ) feature : ( a ) name / key : cds ( b ) location : 41 .. 367 - - ( ix ) feature : ( a ) name / key : mat . sub .-- - # peptide ( b ) location : 140 .. 367 - - ( ix ) feature : ( a ) name / key : sig . sub .-- - # peptide ( b ) location : 41 .. 139 - - ( xi ) sequence description : seq - # id no : 15 : - - agcagagggg ctgagaccaa accagaaacc tccaattctc atg tgg aa - # g ccc atg 55 - # - # met trp lys pro met - # - # - 33 - #- 30 - - ccc tca ccc tcc aac atg aaa gcc tct gca gc - # a ctt ctg tgt ctg ctg103 pro ser pro ser asn met lys ala ser ala al - # a leu leu cys leu leu - 25 - # - 20 - # - 15 - - ctc aca gca gct gct ttc agc ccc cag ggg ct - # t gct cag cca gtt ggg151 leu thr ala ala ala phe ser pro gln gly le - # u ala gln pro val gly - 10 - # - 5 - # 1 - - att aat act tca act acc tgc tgc tac aga tt - # t atc aat aag aaa atc199 ile asn thr ser thr thr cys cys tyr arg ph - # e ile asn lys lys ile 5 - # 10 - # 15 - # 20 - - cct aag cag agg ctg gag agc tac aga agg ac - # c acc agt agc cac tgt247 pro lys gln arg leu glu ser tyr arg arg th - # r thr ser ser his cys 25 - # 30 - # 35 - - ccc cgg gaa gct gta atc ttc aag acc aaa ct - # g gac aag gag atc tgt295 pro arg glu ala val ile phe lys thr lys le - # u asp lys glu ile cys 40 - # 45 - # 50 - - gct gac ccc aca cag aag tgg gtc cag gac tt - # t atg aag cac ctg gac343 ala asp pro thr gln lys trp val gln asp ph - # e met lys his leu asp 55 - # 60 - # 65 - - aag aaa acc caa act cca aag ctt tgaacattca tg - # actgaact aaaaacaagc397 lys lys thr gln thr pro lys leu 70 - # 75 - - catgacttga gaaacaaata atttgtatac cctgtccttt ctcagagtgg tt -# ctgagatt 457 - - attttaatct aattctaagg aatatgagct ttatgtaata atgtgaatca tg -# gtttttct 517 - - tagtagattt taaaagttat taatatttta atttaatctt ccatggattt tg -# gtgggttt 577 - - tgaacataaa gccttggatg tatatgtcat ctcagtgctg taaaaactgt gg -# gatgctcc 637 - - tcccttctct acctcatggg ggtattgtat aagtccttgc aagaatcagt gc -# aaagattt 697 - - gctttaattg ttaagatatg atgtccctat ggaagcatat tgttattata ta -# attacata 757 - - tttgcatatg tatgactccc aaattttcac ataaaataga tttttgtaaa aa - # aaaaa 814 - - - - ( 2 ) information for seq id no : 16 : - - ( i ) sequence characteristics : ( a ) length : 109 amino - # acids ( b ) type : amino acid ( d ) topology : linear - - ( ii ) molecule type : protein - - ( xi ) sequence description : - # seq id no : 16 : - - met trp lys pro met pro ser pro ser asn me - # t lys ala ser ala ala33 - 30 - # - 25 - # - 20 - - leu leu cys leu leu leu thr ala ala ala ph - # e ser pro gln gly leu - 15 - # - 10 - # - 5 - - ala gln pro val gly ile asn thr ser thr th - # r cys cys tyr arg phe 1 - # 5 - # 10 - # 15 - - ile asn lys lys ile pro lys gln arg leu gl - # u ser tyr arg arg thr 20 - # 25 - # 30 - - thr ser ser his cys pro arg glu ala val il - # e phe lys thr lys leu 35 - # 40 - # 45 - - asp lys glu ile cys ala asp pro thr gln ly - # s trp val gln asp phe 50 - # 55 - # 60 - - met lys his leu asp lys lys thr gln thr pr - # o lys leu 65 - # 70 - # 75 - - - - ( 2 ) information for seq id no : 17 : - - ( i ) sequence characteristics : ( a ) length : 247 base - # pairs ( b ) type : nucleic acid ( c ) strandedness : double ( d ) topology : linear - - ( ii ) molecule type : dna ( genomic ) - - ( xi ) sequence description : seq - # id no : 17 : - - agcttggata aaagacagcc agttgggatt aatacttcaa ctacctgctg ct -# acagattt 60 - - atcaataaga aaatccctaa gcagaggctg gagagctaca gaaggaccac ca -# gtagccac 120 - - tgtccccggg aagctgtaat cttcaagacc aaactggaca aggagatctg tg -# ctgacccc 180 - - acacagaagt gggtccagga ctttatgaag cacctggaca agaaaaccca aa -# ctccaaaa 240 - - ctttgag - # - #- # 247 - - - - ( 2 ) information for seq id no : 18 : - - ( i ) sequence characteristics : ( a ) length : 77 base - # pairs ( b ) type : nucleic acid ( c ) strandedness : double ( d ) topology : linear - - ( ii ) molecule type : dna ( genomic ) - - ( xi ) sequence description : seq - # id no : 18 : - - agcttgtcga ctaatacgac tcactatagg gcggccgcgg gcccctgcag ga -# attcggat 60 - - cccccgggtg actgact - # - # - # 77 - - - - ( 2 ) information for seq id no : 19 : - - ( i ) sequence characteristics : ( a ) length : 23 base - # pairs ( b ) type : nucleic acid ( c ) strandedness : single ( d ) topology : linear - - ( ii ) molecule type : cdna - - ( xi ) sequence description : seq - # id no : 19 : - - gatccgggcc cttttttttt ttt - # - # 23 - - - - ( 2 ) information for seq id no : 20 : - - ( i ) sequence characteristics : ( a ) length : 20 base - # pairs ( b ) type : nucleic acid ( c ) strandedness : single ( d ) topology : linear - - ( ii ) molecule type : cdna - - ( xi ) sequence description : seq - # id no : 20 : - - aaaaaaaaaa aaagggcccg - # - # - # 20 - - - - ( 2 ) information for seq id no : 21 : - - ( i ) sequence characteristics : ( a ) length : 40 base - # pairs ( b ) type : nucleic acid ( c ) strandedness : single ( d ) topology : linear - - ( ii ) molecule type : cdna - - ( ix ) feature : ( a ) name / key : cds ( b ) location : 6 .. 38 - - ( xi ) sequence description : seq - # id no : 21 : - - atcga agc ttg gat aaa aga cag cca gtt ggg - # att aat ac - # 40 ser leu asp lys arg gln pro - # val gly ile asn 1 - # 5 - # 10 - - - - ( 2 ) information for seq id no : 22 : - - ( i ) sequence characteristics : ( a ) length : 11 amino - # acids ( b ) type : amino acid ( d ) topology : linear - - ( ii ) molecule type : protein - - ( xi ) sequence description : - # seq id no : 22 : - - ser leu asp lys arg gln pro val gly ile as - # n 1 5 - # 10 - - - - ( 2 ) information for seq id no : 23 : - - ( i ) sequence characteristics : ( a ) length : 30 base - # pairs ( b ) type : nucleic acid ( c ) strandedness : single ( d ) topology : linear - - ( ii ) molecule type : cdna - - ( xi ) sequence description : seq - # id no : 23 : - - cagtggatcc tcaaagtttt ggagtttggg - # - # 30 - - - - ( 2 ) information for seq id no : 24 : - - ( i ) sequence characteristics : ( a ) length : 99 amino - # acids ( b ) type : amino acid ( d ) topology : linear - - ( ii ) molecule type : protein - - ( xi ) sequence description : seq - # id no : 24 : - - met lys val ser ala ala leu leu cys leu le - # u leu ile ala ala thr 1 5 - # 10 - # 15 - - phe ile pro gln gly leu ala gln pro asp al - # a ile asn ala pro val 20 - # 25 - # 30 - - thr cys cys tyr asn phe thr asn arg lys il - # e ser val gln arg leu 35 - # 40 - # 45 - - ala ser tyr arg arg ile thr ser ser lys cy - # s pro lys glu ala val50 - # 55 - # 60 - - ile phe lys thr ile val ala lys glu ile cy - # s ala asp pro lys gln 65 - # 70 - # 75 - # 80 - - lys trp val gln asp ser met asp his leu as - # p lys gln thr gln thr 85 - # 90 - # 95 - - pro lys thr - - - - ( 2 ) information for seq id no : 25 : - - ( i ) sequence characteristics : ( a ) length : 741 base - # pairs ( b ) type : nucleic acid ( c ) strandedness : single ( d ) topology : linear - - ( ii ) molecule type : cdna - - ( xi ) sequence description : seq - # id no : 25 : - - aaccgagagg ctgagactaa cccagaaaga tccaattctc aaactgaagc tc -# gcactctc 60 - - gcctccagca tgaaagtctc tgccgccctt ctgtgcctgc tgctcatagc ag -# ccaccttc 120 - - attccccaag ggctcgctca gccagatgca atcaatgccc cagtcacctg ct -# gttataac 180 - - ttcaccaata ggaagatctc agtgcagagg ctcgcgagct atagaagaat ca -# ccagcagc 240 - - aagtgtccca aagaagctgt gatcttcaag accattgtgg ccaaggagat ct -# gtgctgac 300 - - cccaagcaga agtgggttca ggattccatg gaccacctgg acaagcaaac cc -# aaactccg 360 - - aagacttgaa cactcactcc acaacccaag aatctgcagc taacttattt tc -# ccctagct 420 - - ttccccagac accctgtttt attttattat aatgaatttt gtttgttgat gt -# gaaacatt 480 - - atgccttaag taatgttaat tcttatttaa gttattgatg ttttaagttt at -# ctttcatg 540 - - gtactagtgt tttttagata cagagacttg gggaaattgc ttttcctctt ga -# accacagt 600 - - tctacccctg ggatgttttg agggtctttg caagaatcat taatacaaag aa -# tttttttt 660 - - aacattccaa tgcattgcta aaatattatt gtggaaatga atattttgta ac -# tattacac 720 - - caaataaata tatttttgta c - # - # 741__________________________________________________________________________
a new chemotactic cytokine , nc28 or monocyte chemotactic protein - 3 , is provided . fragments of the cytokine comprising its 13 c - terminal amino acids also exhibit chemotactic activity . the polypeptides may be used as anticancer agents or immunomodulators . dna encoding the nc28 / mcp - 3 polypeptides , as well as corresponding vectors and recombinant expression systems , are also provided .