Red blood cell alloimmunizations in beta-thalassemia patients in Casablanca/Morocco: Prevalence and risk factors.

Abstract

We aimed to study the prevalence and risk factors of red cell alloimmunization in β-thalassemic patients. Retrospective study during 9 years (2009-2018) was conducted on 160 β-thalassemic patients transfused regularly in pediatric department of children's hospital in Casablanca, Morocco. The main clinical, demographic and transfusional characteristics of alloimmunized and non-alloimmunized patients were compared. Red blood cells units transfused were leukodeplated and phenotypically matched for RH-KELL systems and for other systems after immunization. Screening and antibody identification were performed by gel-filtration method on BIO-RAD caseds using 3 and 11 red blood cells panels. To detect autoantibodies, autocontrol and direct antiglobulin tests were carried out using polyspecific coombs (IgG/C3d) gel cards. The prevalence of alloimmunizations was 8.75% during the study period. Seventeen alloantibodies identified were directed mainly against antigens of KELL and RH systems: KEL 1 (35.29%), RH 3 (23.52%), RH1 (11.76%), Kpa (11.76%), RH2 (5.88%). Red blood cells autoantibodies had been detected in 6 of 14 (42.85%) of alloimmunized patients versus 12 of 146 (11.76%) of non-alloimmunized patients (P<0.01). Presence of autoantibodies, transfusional interval<3weeks and gender were associated with high rate of red cells alloimmunization. This study proves the data of literature. The presence of red cell autoantibodies appears to be a major risk factors for alloimmunization in thalassemic children, and could advocate specific transfusion guidelines.