SELECTION OF HLA-HPA-MATCHED BLOOD DONORS BY HPA-DNA TYPING WITH FROZEN LYMPHOCYTES ON HLA-MATCHED DONORS

HPA-alloimmunization is a major factor in refractoriness to HLA-matched platelet transfusion. Retrospective studies indicate that although HPA-matched platelet transfusion is effective in such cases, it is extremely difficult to deal with such situations prospectively. We report a case of successful transfusion of HPA-matched platelets selected by HPA-DNA typing with frozen lymphocytes of HLA-matched donors. The patient was a 51-year-old male with CML who developed HLA antibodies after multiple trnasfusion of random platelets. However, HLAmatched platelets were ineffective. Further serological tests including monoclonal antibodyspecific immobilization of platelet antigens (MAIPA) revealed that he also possessed HPA-3a antibody, which appeared to be responsible for the refractoriness. HPA-DNA typing by the PCR-SSP method indicated that his HPA-3 type was b/b and those of refractory donors were HPA-3a/a or HPA-3a/b. By HPA-3 typing with 122 frozen lymphocytes of HLA-matched donors, 14 donors were found to be HPA-3b/b. HLA-HPA matched platelets from these donors were shown to be effective, indicating that refractoriness in this patient was due to HPA-3aalloimmunization. The method described here for selection of HLA-HPA matched donors is effective under the following circumstances: 1) a considerable number of HLA-matched donors and their frozen lymphocytes are available; 2) HPA matching frequency of a given case is not rare; and 3) transfusion of matched platelets is expected to be terminated in a limited period.