A Cross‐matching Procedure for the Selection of Platelet Donors for Alloimmunized Patients

Abstract

A platelet cross-matching procedure was assessed for selecting compatible donors for alloimmunized patients. This confirms the clinical value of combining an indirect platelet immunofluorescence test (PIFT) with a lymphocytotoxicity test (LCT) in predicting the survival of single-donor platelets. There was good agreement between the PIFT cross-match and post-transfusion platelet recovery. Compatibility in the LCT alone was insufficient for platelet donor selection; this test did not detect all antibodies affecting platelet survival. Positive LCT and PIFT cross-matches indicated the presence of HLA antibodies. Inclusion of an indirect lymphocyte immunofluorescence test (LIFT) helped to classify the platelet antibody when the LCT cross-match was negative. In such cases, parallel positive findings with the LIFT and PIFT suggested a cytotoxic-negative antibody of probable HLA specificity active against platelets. Disparity between the LIFT and PIFT was also observed; a strongly positive PIFT along with a weak reaction in the IIFT suggested that a platelet-specific antibody was responsible for the poor platelet survival in these cases. The presence in multitransfused patients of LIFT-positive antibodies not reacting in the LCT and PIFT, which do not affect the survival of transfused platelets, was shown. A positive granulocyte cross-match was demonstrated in patients with febrile rigors associated with compatible platelet transfusions. Splenectomy and steroids may improve the survival of incompatible platelets depending on the nature of the platelet antibody.