Gorilla RH-like genes and antigens

It has been previously shown that most of the human IgG monoclonal D-specific antibodies define a polymorphism in the gorilla consisting of two phenotypes: D-gor-positive and D-gor-negative. By quantitative indirect immunofluorescence assay and quantitative immunoblotting it was evaluated that the number of D-gor antigenic sites per gorilla red cell varies from a level equivalent to that observed for human RhD positive cells to a level eight times higher. By immunoblotting with a rabbit reagent specific for the carboxylic end of human Rh-polypeptides it was demonstrated that RBCs from all gorillas, whatever their D-gor phenotype, possess 33000 relative molecular mass Rh-like polypeptides. The expression of the D-gor antigen was shown to be associated with the presence of three polymorphic bands defined by Southern blot using a human exon 4 RHCE probe, and to a length polymorphism of gorilla intron 3 evidenced by polymerase chain reaction. By contrast, the expression of the D-gor antigen was not associated to the length polymorphism of gorilla intron 4 which is related to the presence or absence of an Alu-Sx element in intron 4, paralleling the situation observed in human. These results confirmed the presence in the gorilla genome of at least two RH-like genes, one of which being responsible for D-gor polymorphism. The phylogenesis of the human and gorilla RH genes is discussed in light of the comparison of intron 4 sequences.