Abstract
Group B and AB sera, acting on O red cells in the presence of UDP-galactose, each converted them into B active cells, which were agglutinated by anti-B human serum (1:512) at the titer of 128-fold, while group Bm and A-1 Bm sera, converted O red cells similarly incubated into B active cells, which were agglutinated by anti-B human serum (1:512) at the titer of 8- to 16-fold. This indicates that alpha-galactosyltransferase activity in Bm and A-1 Bm sera may be about 1/8-1/16 that in B and AB sera. Group CisAB sera, even after absorption of cold anti-B agglutinins with packed, washed group B red cells, did not convert O red cells in the presence of UDP-galactose in such a way that they might agglutinate against anti-B human serum.