Red Blood Cell Alloimmunization in Sickle Cell Disease Patients in Tanzania.

Objective: Alloimmunization is a recognized complication of red blood cell (RBC) transfusion and causes delayed hemolytic transfusion reactions and provides problems sourcing compatible blood for future transfusions. The objective of this study was to determine the frequency of RBC alloimmunization in SCD patients in Tanzania where pretransfusion screening for alloantibodies is not practiced.

Methods: In a cross-sectional study, SCD patients at Muhimbili Hospital Sickle Cell Clinic, Dar es Salaam, Tanzania, were investigated. The demographic characteristics and transfusion history were recorded. Blood samples were drawn from consenting, previously transfused patients and RBC alloimmunization was demonstrated using immunohematologic techniques.

Results: There were 365 patients (median age, 16 years; 55.3% female) and they had received a median of 2 transfusion episodes. Fifteen patients (4.1%) possessed RBC alloantibodies. A total of 61 alloantibodies was found; 16 (26.2%) and 11 (18.0%), were directed against Kell and Rh blood group antigens, respectively.

Conclusion: The rate of RBC alloimmunization in Tanzanian SCD patients was 4.1%. The low transfusion load may explain this immunization frequency. Nevertheless, our study confirms the significance of RBC alloimmunization as a complication in Tanzanian SCD patients. Therefore, there is need to improve immunohematologic testing in Tanzania so that RBC alloimmunization and its consequences may be prevented.