a host resistance factor which is particularly suitable for manufacture by recombinant dna techniques in accordance with this invention is human lysozyme as found in human milk . human lysozyme , as indicated hereinabove , is found in human milk and serves , among other things , to protect the infant from bacterial infection . in fact , it has even been proposed to employ human lysozyme derived from human milk to enrich synthetic cow milk - based formula so that the lysozyme - enriched cow - based infant formula more closely approximates human milk with respect to lysozyme content and activity , see the article by b . haneberg et al . entitled “ lysozymes in feces from infants and children ” which appeared in acta paediatr scand . 63 : 588 - 594 ( 1974 ). also , with respect to the utilization of lysozyme in infant formula so as to enhance the biological value of infant formulas based on cow &# 39 ; s milk , reference is made to the article by t . sh . sharmanov et al . entitled “ multicomponent additive for infant formula enriched with essential and protective factors ”, kazakhstan division of the institute of nutrition , ussr academy of medical science , alma - ata , published in vopr . pitan 1986 , # 3 , pp . 59 - 62 ( 1986 ). of special interest with respect to the preparation or production of human lysozyme by genetic engineering dna techniques for the production of a recombinant human lysozyme , reference is hereby made to epo application 181 , 634 , published jun . 21 , 1986 . this european patent publication discloses dna genetic engineering techniques employing the gene for human lysozyme including a method of preparing a vector containing the gene , the transformation of cells with the vector containing the lysozyme gene and the culturing of the transformed cells for the production and recovery of the resulting produced recombinant human lysozyme . it is disclosed that the recombinant human lysozyme thus produced had functional applications for anti - inflammation , hemostatic , tissue regeneration and anti - tumor . it also discloses other applications for use of human lysozyme in an eye wash as an anti - inflammation enzyme and as a food antiseptic . human lysozyme has advantages over non - human lysozyme , such as egg white lysozyme , since it does not have side effects due to the body &# 39 ; s immune response when used for medical purposes . this european patent publication clearly teaches the production of recombinant human lysozyme , a product useful in the practices of this invention . another compound of special interest in recombinant form as produced by dna genetic engineering techniques for use in compositions in the practices of this invention is human lactotransferrin or human lactoferrin which is found in human milk and which has been characterized and identified as a glycoprotein . specifically , the polypeptide chain of human lactoferrin has been identified and found to possess two glycosylation sites to which glycans are linked through an n -( ê - aspartyl )- n - acetylglucosaminylamine bond and which are structurally heterogeneous . accordingly , the make - up and structure of human lactotransferrin is known . recombinant lactotransferrin or lactoferrin ( lf ) is particularly useful as a component in the preparation of compositions in accordance with this invention and the use of such compositions . the functional role of lactotransferrin in human milk , particularly its role in iron absorption and its role in protection against enteric infection in a newborn infant is described in an article entitled “ lactoferrin in human milk : its role in iron absorption and protection against enteric infection in the newborn infant ”, published in archives of disease in childhood , vol . 55 , pp 417 - 421 ( 1980 ). this article emphasizes that human milk is unusually rich in lactoferrin and that lactoferrin was first reported in 1939 by the investigators , m . sorensen et al . in an article entitled “ the proteins in whey ”, published by c . r . lab ( carlsberg )[ ser chim ], vol . 23 , pp . 1 55 - 59 ( 1939 ). the role of a lactoferrin in human milk is the subject of the article entitled “ iron - binding proteins in milk and resistance to escherichia coli infection in infants ” by j . r . bullen et al ., published in the british medical journal , pp . 69 - 75 ( jan . 8 , 1972 ). further , the article by j . d . oram et al . entitled “ inhibition of bacteria by lactoferrin and other iron - chelating agents ”, published in biochimica et biophysica acta , 170 , pp . 351 - 365 ( 1968 ), discloses that human lactoferrin when not fully saturated with iron is bacteriostatic with respect to bacillus stearothermophilus and bacillus subtilis , both in the presence and absence of trace amounts of metals . another article of interest as to the role of lactoferrin is the article of t . m . cox et al . entitled “ iron binding proteins and influx or iron across the duodenal brush border — evidence for specific lactotransferrin receptors in the human intestine ”, biochimica et biophysics acta , vol . 588 , pp . 120 - 128 ( 1979 ). this article discloses that lactotransferrin coats the luminal surface of the small intestine and shows a remarkable physio - chemical homology with other transferrins and that the proteins may be distinguished from human serum transferrin by its immunological properties , its glycan sequences , its conformation and by the localization of the two iron - binding sites on the protein . still another article by g . spik et al . entitled “ characterization and properties of the human and bovine lactotransferrins extracted from the faeces of newborn infants ”, published in acta paediatr scan , 71 : 979 - 985 ( 1982 ), discloses that when a cow &# 39 ; s milk diet for infants is supplemented by partially or completely iron - saturated human or bovine lactoferrin , the amount of copro - lactotransferrin excreted depended on the origin and on the iron saturation of the lactotransferrin . this article stated that the lactoferrins ingested by babies are not completely destroyed and keep their functional ability to bind iron and thus may supplement the protective bacteriostatic effects of the endogenous lactotransferrin in the intestinal tract . accordingly , in view of the above , it is obvious that much is known about the physical and chemical structure and make - up of human lactotransferrin and its utility when present in an infant diet . further , the article by b . reiter entitled “ the biological significance and exploitation of some of the immune systems in milk — a review ”, published in microbiologie — aliments — nutrition , vol . 2 , pp . 1 - 20 ( 1984 ), reviews the human resistance factors or protective proteins found in human milk including the immunoglobulins , complements , lysozyme , lactoferrin , lactoperoxidase and others . in this article , special attention is given to the functional and protective roles of lysozyme in human milk and it is disclosed that feeding lysozyme to infants increases the immunoglobulin level in faeces ( secretory iga ) compared with the faeces of infants fed formula feed only . this article also discloses the role of lactoferrin in inhibiting bacteria . lactoperoxidase is also discussed in this article and its bactericidal effect in human milk , see also the article by j . h . brock entitled “ lactoferrin in human milk . its role in iron absorption and protection against enteric infections in the newborn infant ” published in archives of diseases in childhood , 55 , pp . 417 - 421 ( 1980 ). of special interest is the article by g . e . gaull et al . entitled “ growth modulators in human milk : potential roles ”, published by pediatrics pp . 156 - 160 . this article mentions that there are at least three major groups of non - cellular constituents in human milk . these groups comprise : 1 ) the so - called classical nutrients , i . e . proteins , lipids , lactose , vitamins and the major and trace minerals ; 2 ) the so - called protective or human host resistance factors , such as secretory iga mentioned herein ; and 3 ) a newly recognized functional group consisting of growth modulators which includes small molecules , such as taurine , small hormone - like proteins , such as epidermal growth factor ( egf ), enzymes and interferons . the last mentioned growth modulators are also protective factors . all these factors or groups are useful when chemically synthesized or in recombinant form in compositions in accordance with this invention . further , of special interest in the practice of the present invention is the paper by r . e . mcclead et al . entitled “ oral lactoferrin ( lf ) and lactoperoxidase ( lp ) decrease mortality of enterotoxigenic e . coli ( etec ) infection ”, presented at the american pediatric society / society of pediatric research — april , 1987 wherein it is concluded that supplemental feedings of lactoferrin at concentrations comparable to that in human milk decrease mortality from etec in suckling mice and that high concentrations of lp but not of lz are also protective . this article speculates that infant formula containing lf and / or lp may prevent enteric infections in the newborn . another article of interest in connection with the practices of this invention is the article by s . k . polberger et al . entitled “ growth and metabolic responses in very - low - birth - weight infants ( vlbw ) infants fed with ultrafiltrated human milk protein fortified fresh breast milk — a model for optimal feeding of vlbw - infants ?” also presented at the meeting of american pediatric society / society of pediatric research — april 1987 . this article indicates that human milk protein obtained by ultrafiltration of human milk is nutritionally useful when employed to fortify the mother &# 39 ; s own fresh human milk and that a significant correlation was found between protein intake and growth , serum urea , plasma , prealbumin and transferrin as well as many plasma and urine amino acids , with the optimal nutritional protein intake from human milk protein in vlbw — infants being between 3 . 0 and 3 . 5 g / kg / d . further , in another such article by b . l . nichols et al . entitled “ human lactoferrin fortification of formulas promotes thymidine uptake into dna of rat intestinal crypt cells ” also presented at meeting of american pediatric society / society of pediatric research — april 1987 , there is disclosed that cow milk - based and soy protein - based formulas to which lactoferrin has been added reverses the inhibition of thymidine uptake into the dna of rat intestinal crypt cells as compared with the same formulas without the addition of human lactoferrin . the above disclosures clearly indicate the advantages in accordance with this invention of incorporating into synthetic infant formulas that are cow milk - based and / or soy - based , one or more of the recombinant nutritional and / or functional human milk proteins including one or more of the recombinant host resistance factors found in human milk . many of the human proteins including the host resistance factors of human milk are obtained by ultrafiltration from pooled human milk . as noted herein , there is a danger that the pooled human milk might be contaminated with hiv or other dangerous viruses . this is one reason in accordance with the practices of this invention that the nutritional and / or functional human milk proteins including the host resistance factors of human milk , all as described hereinabove , be prepared and produced by chemical synthesis or by genetic engineering techniques . such produced human milk proteins would be free of hiv and / or other dangerous viruses and could be produced in substantial amounts without dependency on the availability or supply of human milk . moreover , in accordance with this invention , such human milk proteins could be specially produced , such as human lysozyme and human lactotransferrin so that , in effect , tailor - made recombinant human milk protein compositions containing only , for example , human lysozyme or only human lactoperoxidase or human lactoferrin or human secretory iga and others , or combinations thereof , could be produced in high purity . the production of human milk proteins by recombinant dna techniques permits greater flexibility in the make - up and utilization of compositions in accordance with this invention when utilized to enhance the diet of infants , particularly vlbw infants or to enhance the nutritional and / or functional value of synthetic infant formulas , either cow milk - based , soy protein - based or meat - based , as indicated hereinabove . instead of recombinant human milk proteins , one could employ in the practices of this invention human milk proteins produced by chemical synthesis where applicable or desired . such chemically synthesized human milk proteins , like the corresponding recombinant proteins , would also be free of hiv and accordingly would also be usefully employed in the practices of this invention . as will be apparent to those skilled in the art in the light of the foregoing disclosures , many modifications , alterations and substitutions are possible in the practices of this invention without departing from the spirit or scope thereof .
compositions containing human milk proteins , including the so - called host resistance factors of human milk , prepared by chemically synthesizing the human milk proteins or by genetic engineering techniques for producing recombinant human milk proteins , are useful for supplementing or enhancing the diet of infants , particularly very - low - birth - weight infants . the human milk proteins include the host resistance factors found in human milk , such as lactoferrin , lactoperoxidase , lysozyme , immunoglobulin - a , alpha - lactalbumin , alpha , beta , kappa - caseins , and others . the compositions may also include components other than the human milk proteins useful for improved infant nutrition . in the utilization of the compositions of this invention , the compositions would be administered to an infant in at least an amount that the infant would receive if fed substantially only fresh human milk . also , the proportions of the human milk proteins would preferably be present in the compositions in about the proportions these proteins are found in human milk .