Erythrocyte alloimmunization in children with sickle cell anemia living in Kilifi, Kenya

1. Erythrocyte alloantibodies from the Rhesus, MNS, Lewis and Lutheran blood groups are present in multiply transfused children with sickle cell anemia. 2. Screening for alloantibodies and extended antigen matching in individuals with sickle cell anemia will improve transfusion safety. Sickle cell anemia (SCA) management in sub-Saharan African relies on transfusion, whose safety is compromised by lack of extended blood group matching beyond ABO and Rhesus D antigens, plus absence of routine alloantibody screening. To determine the incidence of erythrocyte alloimmunization in multiply-transfused children with SCA in Kilifi, Kenya, we retrospectively studied 98 children with SCA, admitted to Kilifi County Referral Hospital from 2003-2023. Plasma samples collected over the follow-up period through a routine ward surveillance study were screened for alloantibodies. Alloantibodies were detected in 14/98 (14.3%) participants and an autoantibody was detected in 1/98 (1.0%). Anti-e was found in two children, while anti-E, anti-M, anti-S, anti-s, anti-Lu a & anti-Le b were each found in single individuals. Five children had pan-reactive alloantibodies and three had antibodies of unidentified specificity. Older age was significantly associated with the development of alloantibodies ( P = 0.027). Our alloimmunization rate of 14.3% is higher than previously reported from East Africa (2.9-8%). Since most alloantibodies were specific to Rhesus and MNS blood groups, and older age was significantly associated with alloimmunization, this underscores the importance of routine alloantibody screening in multiply-transfused children and suggests the need for extended antigen matching in SCA patients to improve transfusion safety.