red blood cell alloimmunization in patients with thalassemia major and intermediate in southwest iran

background: transfusion is the mainstay treatment of patients with thalassemia major and occasionally in thalassemia intermediate. alloimmunization is an unwanted side effect of blood transfusion. the present study intended to determine the frequency of alloimmunization in patients with β- thalassemia major and thalassemia intermediate in southwest iran. patients and methods: this was a cross-sectional study on 133 transfusion dependent β-thalassemia patients at shafa hospital-in southwest iran. the method of antibody screening was the tube method. all panel test phases were done at immunohematology laboratory of iranian blood transfusion organization. results: there were 66 males (49.1%) and 67 females (50.9%) with the mean age of 17.5 years (sd±7.5) included in this study. the antibody screening panel test was positive in 42 patients (32.06%). twenty five patients (18.7%) had alloantibody and 17 patients (12.7%) also had autoantibody. the predominant pattern of alloimmunization was alloantibodies against rh sub groups system in 55 percent of patients and 33% of patients had alloantibodies against kell system. three important factors that significantly influenced the frequency of alloimmunization were: age at the first blood transfusion, splenectomy and β- thalassemia intermediate. conclusion: alloimmunization is a common complication among patients with transfusion dependent β-thalassemia in khuzestan province, iran. matching the selected donors with recipients based on the extended red blood cell antigen typing may decrease the incidence of alloimmunization. key words: alloimmunization, thalassemia major, thalassemia intermediate, rh blood group, kell blood group.