Red blood cell alloimmunization from an African perspective

Purpose of review Red blood cell (RBC) alloimmunization occurs when individuals are exposed to erythrocytes that express blood group antigens different from their own. Consequences of alloimmunization include hemolytic disease of the fetus and newborn and hemolytic transfusion reactions, with potentially serious morbidity and mortality. Patients who formed antibodies showed a four to five times increased risk for additional alloantibodies upon further transfusion exposure and may be at increased risk for transfusion reactions. In view of the main transfusion indications in Africans (e. g. malaria and pregnancy), the lifetime risk of exposure to multiple transfusion events is substantial, stressing the need for information on RBC alloimmunization in African transfusion recipients. Recent findings Three cross-sectional studies on RBC alloimmunization from two African countries of Uganda and Malawi showed that 1-6% of transfused patients possessed clinically relevant RBC antibodies. Summary Regarding RBC compatibility testing for transfusion, ABO/D typing is mandatory in African settings but complete crossmatches are not routinely performed. Despite the limited data on posttransfusion alloimmunization, a complete crossmatch for patients with past transfusions could be recommended. However, more information on blood group distribution in Africans and RBC alloimmunization rates and specificity is needed to consider immunoprophylaxis for hemolytic disease, pretransfusion testing, and preventive strategies to avoid transfusion-induced alloimmunization.