Variability in rates of alloimmunization in different groups of children with sickle cell disease: effect of ethnic background.

We evaluated the incidence of red blood cell alloimmunization in children with sickle cell disease from different backgrounds using standard blood banking techniques. Transfusion number, sequence of antibody formation, and antigen phenotyping were analyzed. Children with non-American ethnic origins had a 42.9% incidence of alloimmunization compared to 17.6% in American patients. Antigen frequencies were similar in the two groups. Fewer transfusions resulted in more antibodies in the non-American children. We recommend that all sickle cell patients be fully phenotyped prior to initiation of transfusion therapy. Phenotypically matched units do not appear to be indicated for the majority of sickle cell patients receiving either simple or hypertransfusion, but should be considered for patients of non-American ethnic origin once such patients become immunized.