Abstract
1) The inhibiting activity of N-acetyl-D-galactosamine, its several derivatives and some other sugars was investigated in the agglutination systems of A cells by human anti-A isoagglutinins, immune sera, anti-A lectins of Phaseolus limensis (Lima beans var. Willow leaf) and Dolichos biflorus, and also in the rabbit anti-A sheep cell hemolysis system. 2) The agglutinations of A cells by a normal human anti-A serum (α(No. 0582)), and by the lectins were inhibited with N-acetyl-D-galactosamine and its pyranosyl derivatives. The inhibition data elucidate that the pyranose form of N-acetyl-D-galactosamine is responsible for the blood-group A activity. 3) The experimental results indicated that if linked, N-acetyl-D-galactosamine must be present in α-glycosidic linkage to exert full serological activity. 4) Interaction between the serologically active form of N-acetyl-D-galactosamine and the anti-A agglutinins was discussed.
