Further evidence that carbohydrates are the immunodeterminant structures of blood group M and N specificities

Terminal beta-D-galactopyranosyl (Gal) groups are implied in blood group N but not M specificity by the following findings: (a) Rabbit anti-asialoganglioside sera specific for terminal beta-Gal-(1 leads to 3)-GalNac agglutinate human group 0 M and N erythrocytes, the latter to a significantly higher titer, while rabbit anti-ganglioside GMl sera, whereas sialic acid modifies the antibody specificity, do not. The agglutination score with N erythrocytes was about twice that with M red blood cells. The asialoganglioside antibodies were readily absorbed by group 0 N erythrocytes, which were up to 10 times more efficient than group 0 M erythrocytes. Erythrocyte agglutination by the anti-asialoganglioside sera was inhibited by M and N antigen preparations isolated from group 0 red cells ghosts. N antigen was a better inhibitor. Asialoganglioside effectively inhibited the red cell agglutinations by anti-asialoganglioside serum. Ganglioside GMl did not inhibit. (b) Horse anti-pneumococcus Type XIV serum, which has anti-beta-Gal specificity, precipitated highly active N but not M substances. This precipitation was specifically inhibitable by oligosaccharides with terminal beta-Gal. (c) Beta galactosidase specifically inactivated native N and "acid-produced' N substances with the release of about three moles Gal per subunit of N antigen. It did not affect M antigen.