Differences between Rh(D) negative subjects in response to Rh(D) antigen.

Abstract

Summary Further evidence is produced of the existence of two kinds of Rh negative subject: the first forms anti‐Rh after a single injection although sometimes in such a low concentration that a clearance study with a small dose of Rh positive red cells is required to detect it; antibody usually becomes detectable serologically after a second, spaced injection; the second kind of Rh negative subject fails to form anti‐Rh even after several injections and has a repeatedly normal survival of Rh positive red cells and may be incapable of becoming immunized to the Rh antigen. In the present series of 34 Rh negative subjects, approximately 50% became immunized following injections of Rh positive red cells; the number is not significantly different from the incidence of approximately 60% reported in other published series. Some further evidence is provided that the rate of clearance of Rh positive red cells is more sensitive than any serological test in indicating the presence of a low concentration of anti‐Rh and that different examples of anti‐Rh in presumably similar concentrations in the plasma produce very different rates of red cell clearance. Of seven subjects given at least two injections of D positive Bua‐positive red cells, four formed anti‐D, but only one formed anti‐Bua.