[Interaction between normal A1 or A2 and B alleles in the AB heterozygote. Comparative study of European and African families].

A comparative study of European and African families is described to demonstrate interaction between A1 and A1B, A2 and A2B, B and A1B, B and A2B phenotypes who have either the same A allele or the same B allele. The quantitation of the agglutination has been determined by the "agglutination percentage measurement". The following reagents were used: human anti-A and anti-B, anti-A1 extracted from Dolichos biflorus and anti-H serum extracted from Ulex europaeus. In the A1 and A1B families--who received the same A1 allele--a weaker agglutination by anti-A1 and anti-A is observed in A1B Africans. In the A2 and A2B families who received the same A2 allele, the agglutination with anti-A is depressed from A2 to A2B in the European and African populations. In the B and A1B families who received the same B allele, a weakened agglutination between B and A1B with anti-B is only observed for the A1B Europeans. In the B and A2B families who received the same B allele, there is no variation of the agglutination between B and A2B with anti-B. The H status is the same for European and African populations, although the B Africans had less H but more B than Europeans. The results of our study led to the observation that the Africans have H deficient or a strong B gene. Like SSEBABI, we think that a strong B gene is perhaps acting more intensely on H substrate than A1.