Expression of B and H antigens on red cells from a group B(weak) individual studied by serologic and scanning...

The proposita was classified as B(el), B(y), or B(m), Le(b+) by routine blood grouping and by adsorption/elution studies using anti-A and -B hyperimmune pregnancy sera. Red cells from the proposita adsorbed as much anti-B from the hyperimmune sera as did red cells from normal B individuals, but adsorbed less anti-A,B (group O serum). Saliva contained H, but not B, soluble substance. Red cells from the proposita and a normal B donor were sensitized with monoclonal A and B blood group antibodies immunolabeled with colloidal gold particles, and examined in a scanning electron microscope. B antigens were found on more than 95 percent of normal B cells, but on only 2-3 percent of red cells from the proposita. However, when the same cells were sensitized with anti-A,B that reacted strongly with B oligosaccharides other than type 2 chains, half of the labeled red cells from the proposita were labeled more strongly than any normal B cells. Our results explain why red cells from the proposita adsorb significant amounts of anti-B and anti-A,B without being agglutinated by these antibodies. The results of both adsorption/elution and immunolabeling suggest that the B antigen on her cells differs biochemically from that on normal B cells.