Complexity of the Rh antigen demonstrated by comparative tests using antisera of human and primate origins.

Comparative analysis of two antisera, one produced in chimpanzee and another of human origin, demonstrates the existence of a spectrum of antibodies directed against at least four antigenic determinants connected with Rh reactivity. Some of the determinants are shared by chimpanzee and human red cells, while others are restricted to one species only. Based on this study, it is suggested that both the human Rh(D)-positive type and its chimpanzee counterpart, the Rc-positive type, could be of common origin, while the negative types are the results of later, parallel events during evolution.