A “D-Like” Antigen in Rhesus Monkey, Human Rh Positive and Human Rh Negative Red Blood Cells

Summary A D-like antigen has been demonstrated in rhesus monkey, human Rh positive and Rh negative red cells. These, as well as heat extracts of human Rh positive or Rh negative red cells, induce formation of D-like antibodies in guinea pigs. The latter antibody seems to act on a site on the Rh positive red cell surface which is different from the true human D (Rho) site. Whether produced by any one of the antigenic materials described, D-like antibodies in guinea pigs on exposure either to rhesus monkey, human Rh positive or Rh negative red cells, yielded eluates of D-like specificity. The antigen on the red cells important in clinical medicine is defined by reactions with human anti-D sera. The term “rhesus factor” as applied to the human D (Rho) antigen appears to be a misnomer. In the absence of any known antigenic stimulus, D-like antibodies were demonstrated occasionally in normal guinea pig sera.