Monogamous bivalency of IgG antibodies. I. Deficiency of branched ABHI-active oligosaccharide chains on red cells of infants causes the weak antiglobulin reactions in hemolytic disease of the newborn due to ABO incompatibility.
This study shows that monogamous bivalency of human IgG anti-A and anti-B is necessary to maintain sensitization of red cells in the antiglobulin test. On red cells of infants and of adults of i phenotype, the known deficiency of branched ABHI-active oligosaccharide chains limits monogamous bivalency, and these accounts for the relatively weak direct antiglobulin reactions in hemolytic disease of the newborn due to ABO incompatbility. One corollary of this finding is that there is strong biologic selection against the transition on fetal red cells from the straight-chain i phenotype to branched-chain I phenotype, since such branching of cell-surface oligosaccharide chains would compromise ABO-incompatible pregnancies.
D000017:ABO Blood-Group System; D000906:Antibodies; D001787:Blood Group Incompatibility / Q000276:immunology; D055598:Chemical Phenomena; D002621:Chemistry; D003298:Coombs Test; D004220:Disulfides / Q000378:metabolism; D004899:Erythroblastosis, Fetal / Q000276:immunology; D004912:Erythrocytes / Q000276:immunology*; D005260:Female; D005312:Fetal Blood / Q000276:immunology; D006801:Humans; D007048:I Blood-Group System; D007074:Immunoglobulin G; D007231:Infant, Newborn; D009844:Oligosaccharides / Q000276:immunology*; D011247:Pregnancy
D000017:ABO Blood-Group System; D000906:Antibodies; D004220:Disulfides; D007048:I Blood-Group System; D007074:Immunoglobulin G; D009844:Oligosaccharides