STUDIES ON HUMAN ANTIBODIES

Abstract

Human antibodies to blood group A substance were purified by absorption on columns of insoluble polyleucyl hog blood group A + H substance and eluted first with N-acetylgalactosamine and then with an A active reduced pentasaccharide ARL0.52. The γM and γG antibodies in these eluates were separated by density gradient centrifugation. The antibodies were studied for their relative capacities to be inhibited by various blood group A active oligosaccharides. Antibodies eluted by the N-acetylgalactosamine could be inhibited by N-acetylgalactosamine, as well as by lower concentrations of A active tri- and pentasaccharides, while those eluted by the pentasaccharide ARL0.52 could only be inhibited by the two oligosaccharides, but not by N-acetylgalactosamine, indicating that the N-acetylgalactosamine eluate had more antibodies with smaller size combining sites than the ARL0.52 eluate. Measurements by equilibrium dialysis gave values ranging from 2 x 103 to 1 x 105 M–1 and the values obtained with the ARL0.52 eluate were somewhat higher than those with the GalNAc eluate. Only one of three anti-A sera had γM anti-A in the ARL0.52 eluate, while all three had γM in the N-acetylgalactosamine eluate. Data on the precipitating, hemagglutinating, complement fixing, hemolytic properties of the eluted antibodies, and of their content of κ and λ light chains are given.