Transfusion in Sickle Cell Disease: Risk Factors for Alloimmunization

Sickle cell patients have a high prevalence of alloimmunization. This high rate of alloimmunization can be partially explained by the existence of an antigenic difference between the predominantly Caucasian donor population and the sickle cell patients of African origin. Genetic and environmental risk factors have also been described. The main risk factors that have been shown in retrospective or cross-sectional studies are some HLA alleles, the age of the patient, the number of leukocyte-depleted erythrocyte concentrates (CED) transfused, the number of transfusion episodes, the age of the CEDs, the existence of an inflammatory event at the time of transfusion and the presence of anti-erythrocyte autoantibodies.There is also evidence of an impaired TH response but the underlying immunological mechanism is not fully understood. The aim of this study is to study the prevalence and the risk factors for anti-erythrocyte alloimmunization and to try to understand the immunological mechanisms.