[Serum glycosyltransferase activity associated with antigen biosynthesis in blood groups A and B. Study of normal B group and cis AB group subjects].

Two groups of alpha-D-galactosyltransferase activity were described in the sera of 132 caucasian B donors of the National Centre of Blood Transfusion, Paris. The group having the lowest activity represented 84% of the caucasian population, the second one: 16%. They were related neither to the secretory status nor to the genotype of the individuals studied. In some of the 20 african sera studied a third group of activity could be defined. In the caucasian population, these groups were clearly correlated to the agglutinability of the red cells by anti B serum. But no clearcut agglutinability groups could be defined. In the african heterogeneous population, there was no relationship between the two parameters. We did not find the third group of Gibbs. The agglutinability of the B red cells by anti-H (Ulex europaeus) varied inversely as transferase activity and two relationships were distinguished according to the ethnical origin. Only in the caucasian population, this phenomenon was in close relationship with the B agglutinability. Glycosyltransferases activities associated to the biosynthesis of A and B blood group antigens were looked for in 12 cis AB samples from 5 families. The alpha-N-acetyl-D-galactosamyltransferase activity was always weaker than that of normal A and AB sera except for A/cis AB genotype individuals. The presence of alpha-D-galactosyltransferase activity was demonstrated using 2' fucosyllactose as acceptor and by transformation of O red cells into weak B active ones.