Human blood-group A- and H-specified glycosyltransferase levels in the sera of newborn infants and their mothers.

The level of blood-group A1-specified alpha,3'-N-acetyl-D-galactosaminyl-transferase in the serum of recently-delivered women was found to be appreciably lower than the level of this enzyme in the serum of non-pregnant adults and of newborn infants; a similar but less striking decrease was observed in the levels of the A2-specified alpha,3'-N-acetyl-D-galactosaminyltransferase and the H-specified alpha,2'-L-fucosyltransferase. Although the red cells of newborn infants are known to have relatively few A and H antigen sites, the serum of neonates was found to have a level of A1- and A2-dependent N-acetylgalactosaminyltransferases and H-dependent fucosyltransferase as high as, if not higher than, the serum of non-pregnant adults. This finding is compatible with the fact that the haemopoietic tissue contributes only about 20% of the serum transferase level.