The Bp Graded Blood Group System of the Baboon: Its Relationship with Macaque Red Cell Antigens

Abstract

The first blood group system to be defined in baboons by means of isoimmune agglutinating reagents is composed of five graded types: B₄, B₃, B₂, B₁and b, inherited, as postulated, by five allelic genes with decreasing dominance order. There are significant differences in distribution of the B^p blood groups between hamadryas baboons on the one hand, and cynocephalus and anubis on the other, which may serve as auxiliary taxonomic criteria. Antibodies of specificities related to the B^p graded antigens are found in the sera of presumably nonimmunized baboons, and also in the rhesus isoimmune antisera that detect one of the subtypes of the so-called D^rh graded system of macaques. These findings point to ubiquity of the B^p or B^p-like antigens, and to the close serological relationship between B^p baboon and D^rh macaque red cell antigens, perhaps as evidence of a common ancestral antigen which gave rise to a diverging set of graded subspecificities of baboon and macaque red cells, respectively.