Comparative study of human monoclonal anti-D antibodies of IgG and IgM classes in tests with red cells of nonhuman primates

Abstract

Forty-nine human anti-D (Rho) monoclonal antibodies of the IgG and IgM classes were tested with red blood cells of various nonhuman primates, from anthropoid apes to Prosimians, and significant differences in reactivity were observed among antibodies of two classes depending on taxonomic position of primate animals. By and large, higher percentage of IgM mAbs gave positive reactions with nonhuman primate red cells and, particularly, with blood of lower monkeys: Old and New Worlds monkeys and Prosimians, than did those of IgG class. Allotypic reactions with red cells of African apes were produced by majority of IgG mAbs but by very few IgM reagents. Some of those reactions defined epitopes related to human D, such as chimpanzee Rc and gorilla Dgor. By contrast, individual differences among Old World monkey species were revealed almost exclusively in tests using anti-D mAbs of IgM class. Some of the epitopes detected by these antibodies on the red cells of macaques are related to human D alloantigen, as confirmed by absorption experiments. Differences among mAbs evidenced in tests with nonhuman primate red cells reflect the complexity of the immune reactions to the human D antigen.