Clinical significance of non-Rh(D) red cell antibodies

The introduction of anti-Rh(D) immunoglobulin in the mid-1960s has protected the vast majority of Rh negative women at risk from pregnancy-induced isoimmunization and the subsequent possibility of haemolytic disease of the newborn, although a disturbingly high incidence of anti-D is still being observed in pregnant women. Increases in the frequency of blood transfusion (and in the volumes used in many instances) have ensured that many hospital patients will be exposed to foreign red cell antigens outside the ABO and Rh systems. In both these groups, antibodies will continue to be made against isologous red cell antigens, and the non-D Rh antigens, as well as those of many other blood group systems, have become increasingly important in transfusion practice. There is a well recognized disparity between the in vitro demonstration of a red cell antigen-antibody reaction and the in vivo results of introducing this antigen in volume into a recipient with the relevant antibody. This paper reviews the currently available data on in vitro and in vivo red cell antigen antibody interaction, and examines the factors which assume importance in an actual or potential haemolytic transfusion reaction.