BIOSYNTHESIS OF HUMAN BLOOD GROUP T‐, N‐ AND M‐SPECIFIC IMMUNODETERMINANTS ON HUMAN ERYTHROCYTE ANTIGENS

Abstract

On Tn erythrocytes with human sera, UDP-Gal [galactose] and activators T-specific haptenic structures were synthesized in satisfactory yield. The specificity of this biosynthesis was ascertained by agglutination with human and animal anti-T, by specific absorption of human anti-T and by agglutination inhibition assays. With isolated human erythrocyte T antigen as substrate N- and M-specific structures were synthesized with sera from individual human donors in presence of CMP-sialic acid by incubation for 24 h at 37.degree. C. Serology on the recovered product was carried out with 19 monospecific human and animal sera under strictly standardized and controlled conditions with the mandatory tube assay. All M- and N-derived T antigens tested acquired N specificity with all transferase sera of all MN types. M-activation of M- and N-derived T antigens occurred only if the transferase donor had the M gene. The 9 M transferase sera used all gave M-activation of MM- and NN-derived T antigens. None of 12 transferase sera from NN donors M- activated any T antigen. NN antigen was transformed to a M-specific one by all transferase sera from MM donors but by none from NN donors. The biochemical-genetic relation of M to N has not yet been established. N may be the immediate precursor of M or M may originate directly from T. The sialyltransferase responsible for M activation may be a N transferase ''modified'' by the M gene product or an entirely different sialyltransferase.