SUCCESSFUL TREATMENT OF PLATELET TRANSFUSION REFRACTORINESS - THE USEOF PLATELET TRANSFUSIONS MATCHED FOR BOTH HUMAN-LEUKOCYTE ANTIGENS (HLA) AND HUMAN PLATELET ALLOANTIGENS (HPA) IN ALLOIMMUNIZED PATIENTS WITH LEUKEMIA

Six patients, 4 with acute myeloid leukaemia and 2 with a myelodysplas tic syndrome who were refractory to random donor platelet transfusions and alloimmunized to human leucocyte antigens (HLA) and human platele t alloantigens (HPA), were treated with HLA- and HPA-matched platelet transfusions. In all the patients refractoriness and alloantibodies to HLA as well as HPA-1b or HPA-5b were detected simultaneously. Sixty-s even transfusions (445 units) of HLA- and HP4-matched platelets were g iven and responses to them were, in general, satisfactory in all the p atients. No major spontaneous bleeding occurred. Four patients underwe nt bone marrow transplantation despite alloimmunization. The percentag es of platelet transfusion days with a platelet nadir below 20x10(9)/l were 88% for the last 3 random donor platelet transfusions and 39% fo r the first 3 HLA- and HPA-matched platelet transfusions, respectively (p=0.009, Fisher's exact test). Four patients received also HLA-match ed platelets, but responses to them were poor. The small number of tra nsfusions with HLA-matched platelets precluded comparisons to either t he random donor or HLA- and HPA-matched platelet transfusions. It seem s that HLA- and HPA-alloimmunized patients can be successfully support ed with HLA- and HPA-matched platelet concentrates.