High frequency of autoimmunization among transfusion-dependent Tunisian thalassaemia patients.

Abstract Background Limited data are available on the frequency of RBC alloimmunization and autoimmunization in transfusion-dependant Tunisian β thalassaemia patients. Materials and methods We analyzed the clinical and transfusion records of 130 patients (57 females and 73 males; mean age 119months; range 12–11months) with β thalassaemia major and who had regular blood transfusions for periods ranging from 12 to 311months. Results Of the 130 patients, ten (7.7%) developed RBC alloantibodies. The most common alloantibodies were directed against antigens in the Rh systems. Erythrocyte-autoantibodies as determined by a positive direct antiglobulin Coombs test, developed in 52(40%) patients with and without underlying RBC alloantibodies, thereby causing autoimmune haemolytic anaemia in eleven patients (21%). Conclusions Autoimmunization to erythrocyte antigens is a frequent complication in patients with β thalassaemia major. Several factors might have contributed to the high autoimmunization rate observed in this study, including non phenotypic blood exposure and alloantibody formation prior to positive Coombs test.