Studies on human antibodies. 8. Properties and association constants of human antibodies to blood group A substance purified with insoluble specific adsorbents and fractionally fluted with mono- and oligosaccharide.

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 AR(L)0.52. The gammaM and gammaG 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 AR(L)0.52 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 AR(L)0.52 eluate. Measurements by equilibrium dialysis gave values ranging from 2 x 10(3) to 1 x 10(5)M(-1) and the values obtained with the AR(L)0.52 eluate were somewhat higher than those with the GalNAc eluate. Only one of three anti-A sera had gammaM anti-A in the AR(L)0.52 eluate, while all three had gammaM in the N-acetylgalactosamine eluate. Data on the precipitating, hemagglutinating, complement fixing, hemolytic properties of the eluted antibodies, and of their content of kappa and lambda light chains are given.