Carbohydrate-Specific Antibodies in Normal Human Sera

Abstract

IgG and IgM antibodies against several sugars have been characterized in sera of normal donors by passive hemagglutination and a quantitative hemagglutination inhibition test. These antibodies distinguish between the equatorial and axial OH groups at C2, C3, or C4 positions of the glycopyranose configuration, differences between the anomers, linkage types, changes in the primary alcohol group at C6, and OH substitution. In the examples of antibodies to mannose, galactose, and glucose investigated, specificities were usually directed against the β-anomers. In disaccharides, the antibodies appeared to react only with 1 of the 2 sugar subunits, but unlike monosaccharides, the glycosidic linkages also seemed to be a part of the reaction site. Thus, the reacting moiety in gentiobiose was β-D-glucopyranosyl with 1→6 linkage, in cellobiose was β-D-glucopyranosyl with 1→4 linkage, in melibiose was α-D-galactopyranosyl with 1→6 linkage, and in lactose the reaction was directed against β-D-galactopyranosyl with 1→4 linkage. In the maltose-dependent hemagglutination, α-D-glucose appeared to be the main reaction site. ManNAc exemplified the specificity determined by OH group substitution. Antibody to D-Fucose represented example of specificity evolving from substitution of the primary alcohol.