Alloimmunization and erythrocyte autoimmunization in transfusion-dependentthalassemia patients of predominantly Asian descent

The development of hemolytic alloantibodies and erythrocyte autoantibodies complicates transfusion therapy in thalassemia patients. The frequency, cau ses, and prevention of this phenomena among 64 transfused thalassemia patie nts (75% Asian) were evaluated. The effect of red blood cell (RBC) phenotyp ic differences between donors (mostly white) and Asian recipients on the fr equency of alloimmunization was determined. Additional transfusion and pati ent immune factors were examined, 14 (22%) of 64 patients (75% Asian) becam e alloimmunized, A mismatched RBC phenotype between the white population, c omprising the majority of the donor pool, and that of the Asian recipients, was found for K, c, S, and Fyb antigens, which accounts for 38% of the all oantibodies among Asian patients. Patients who had a splenectomy had a high er rate of alloimmunization than patients who did not have a splenectomy (3 6% vs 12.8%; P = .06). Erythrocyte auto antibodies, as determined by a posi tive coombs test, developed in 25% or 16 of the 64 patients, thereby causin g severe hemolytic anemia in 3 of 16 patients. Of these 16, 11 antibodies w ere typed immunoglobulin G [IgG], and 5 were typed IgM, Autoimmunization wa s associated with alloimmunization and with the absence of spleen (44% and 56%, respectively). Transfused RBCs had abnormal deformability profiles, mo re prominent in the patients without a spleen, which possibly stimulated an tibody production. Transfusion of phenotypically matched blood for the Rh a nd Kell (leukodepleted in 92%) systems compared to blood phenotypically mat ched for the standard ABO-D system (leukodepleted in 60%) proved to be effe ctive in preventing alloimmunization (2.8% vs 33%; P = .0005), Alloimmuniza tion and autoimmunization are common, serious complications in Asian thalas semia patients, who are affected by donor-recipient RBC antigen mismatch an d immunological factors, (C) 2000 by The American Society of Hematology.