HLA-matched platelet transfusion therapy of severe aplastic anemia

Abstract

In order to define more clearly the importance of the degree of HLA compatibility in the hematologic support of patients refractory to random-donor platelets, we retrospectively analyzed over 1000 platelet transfusions given during stable periods of their disease to 11 thrombocytopenic, severely alloimmunized patients with aplastic anemia: 28% of the donors fully matched with the recipient for HLA A and B loci (A-matched) and 17% of the donors mismatched with the recipient for two or more HLA antigens (D-matched) provided excellent responses, and 18% of A-matched and 46% of D-matched donors provided poor posttransfusion increments. Among all groups analyzed only A-matched donor-recipient pairs had higher increments than predicted by chance (p < 0.04); no such increments were observed for donor-recipient pairs with lower degrees of HLA compatibility. Cross reactivity, ABO compatibility, and/or absence of HLA-A2 antigen in the recipient did not appear to influence the outcome of platelet transfusions. While HLA-matched platelets are of benefit in selected cases, HLA matching does not reliably predict platelet transfusion responses even in stable patients, and other as yet unknown factors appear to play an important role in determining transfusion outcomes.