Antisera against polypeptide chains derived from M and N blood group glycoproteins.

The polypeptide chains, containing only small amounts of hexosamines, were obtained from M and N blood groups glycoproteins by four cycles of periodate oxidation-Smith degradation, and were used for immunization of rabbits. The antisera obtained precipitated with the Smith-degraded glycoproteins, they reacted much weaker with the desialylated glycoproteins and they did not precipitate the untreated glycoproteins. In the quantitative microprecipitation assay the antisera precipitated better with the antigens of the same blood group specificity (M or N than those used for immunization. This blood group specificity was significantly increased by the cross-absorption of antisera.