Characteristics and natural history of alloimmunization following HLA-matched leukocyte transfusion in Hunter's syndrome

The characteristics and natural history of alloimmunization to HLA were studied in five patients with Hunter's syndrome receiving long term transfusions of leukocytes collected from human leukocyte antigen (HLA) matched donors. Patients were not given any other blood component transfusions. All patients became alloimmunized at an average interval of eight months following an average of 15 transfusions. All patients developed HLA alloantibodies to transfused cross-reactive HLA antigens. Antibodies to transfused incompatible HLA antigens also developed in all patients. Multispecific HLA antibodies in which specificity determination could not be made were also seen in four patients. In a small number of patients in this study, despite matching for the private HLA specificities, HLA alloimmunization was not prevented. In fact, broad alloimmunization was seen uniformly in our patients.