because igg4 levels are usually much smaller than igg2 levels , and the igg4b epitope is expressed on all igg2 alleles and only some igg4 alleles ( kunkel et al. , 1970 ) , the antibody for igg4b is potentially useful to screen a large number of samples for igg2 deficiency .
C0020860
igg4
C0003241
antibody