The Antigenicity of the Rh_o (D^u) Blood Factor

The antigenicity of the Rh variant Rh_o(D^u) was investigated by the transfusion of 45 Rh negative (cde/cde) patients with 68 units of "low grade" Rh_o (D^u) blood of the phenotypes Rh_o(ccD^uee) or Rh₂(ccD^uE). The donor red cells had normal viability; none of the patients made antibodies to Rh_o(D) or Rh_o(D_u).

The results indicate that the inherited, "low grade" Rh_o(D^u) factor is far less antigenic than Rh_o(D). It was also less antigenic than Kell or rh'' (E) in this study. It remains possible that this variant will prove to be antigenic in some recipients, but the hazard from this is undoubtedly much less than has been expected.