HLA antigen and antibody association in platelet-alloimmunized patients.

The frequencies of HLA antigens were compared between 55 patients with and 38 patients without lymphocytotoxic antibodies formation after long-term platelet transfusions. Only HLA-B60 and B75 were found to manifest significant difference between these two groups. Patients with HLA homozygosity had a higher incidence of alloimmunization. Although most of the platelet alloantibodies were against HLA antigens of high frequency, the HLA-antibodies were induced at a rate different from the frequency of their corresponding antigens. The antibodies against the first and second HLA loci are of similar frequencies. In conclusion, the patients with HLA homozygous alleles have a higher incidence of platelet alloimmunization, and the antibody of certain specificities has higher rate of occurrence. These findings may be helpful in platelet-donor selection.