Blood transfusion and alloimmunization in patients with thalassemia: multicenter study.

One of transfusion's side effects is alloimmunization against red blood cell (RBC) antigens. Early diagnosis by antibody screening is an important step in the detection of these alloantibodies. The authors studied the frequency of alloimmunization in thalassemic patients of 4 centers (2 adult and 2 pediatric centers) and compared the rates in children (up to 15 years) and adults. Antibody screening tests were performed by gel method according to its standard pattern and respective program. In positive cases, antibody identification test by gel method was performed. Eight hundred thirty-five patients were studied; 548 (65.6%) were adults (mean age = 24.5), and 287 (34.4%) cases were pediatrics (mean age = 10.05). Of these patients, 74.1% had no history of transfusion reaction, whereas 21 (2.5%) had hemolytic complications. Seventy-eight (9.3%) exhibited allergic symptoms, and 117 (14%) cases experienced febrile reactions during transfusion. Antibody screening showed positive results in 22 pediatric cases (7.7%) and 79 adults (14.4%); 72 (71.3%), 19 (18.8%), 3 (3%), and 1 (1%) cases exhibited single, double, triple, and autoantibodies, respectively. Anti-Kell antibody was seen in 34 (33.7%) cases, anti-D was seen in 11 (10.9%) cases, and anti-E in was seen in 10 (9.9%) cases. The authors observed 8 anti-D+C (7.9%) cases, 1 anti-D+E (1%), 3 anti-Kell+E, 3 anti-Kell+Kpa (3%), and 1 anti-Kell+D double antibodies. These antibodies were also a combination of Rh subgroups or Rh and Kell subgroups. The authors observed meaningful relations between history of transfusion reactions and age with antibody screening results (P = .005). Based on alloantibodies types, more than two thirds of them were Rh subgroups and Kell groups. Phenotype determination of RBCs before beginning chronic blood transfusion and careful cross-matching with Kell and Rh subgroups in addition to ABO may help reduce alloimmunization in chronic transfusion patients.