Platelet antibodies in transfused patients

Abstract

P atients and M ethods We studied sera of 252 patients with haematological or oncological diseases, who received multiple transfusions of rbc and/or platelet concentrates. The aim of our study was to analyse the specificity of platelet reactive antibodies (platelet specific and HLA-antibodies) in a large series of transfused patients. All sera were analysed by platelet immunofluorescence, platelet agglutination, MAIPA and the lymphocytotoxic test (LCT). R esults Platelet reactive antibodies were detected in 113 patients. Among female patients with previous pregnancies 21/36 were alloimmunized but only 7/30 female patients who had not been pregnant (P = 0·0049). In 108 (42·9%) of all sera, we found HLA-specific antibodies. In a subset of 40 sera, reactions of HLA class I antibodies were compared with an identical cell panel using LCT and MAIPA assay. Twenty-nine of these sera showed discrepant results in both techniques. Sera from 20 patients contained platelet specific alloantibodies with defined specificity: HPA-5b (10), HPA-1b (4), HPA-5a (2) HPA-1a (1), HPA-2b (1), HPA-5b + HPA-1b (1), HPA-1b + HPA-2b (1). All sera with anti-HPA-1b contained additional HLA antibodies, 4 sera with anti-HPA-5b apparently contained no HLA-antibodies. Ten sera contained ‘panreactive’ antibodies with broad specificity: GP IIb/IIIa (4), GP IIb/IIIa + Ia/IIa (2), GPIIb/IIIa + Ib/IX (1), GP IIb/IIIa + Ia/IIa + Ib/IX (3). C onclusion (1) Platelet alloantibody specificities in transfused patients (predominantly anti-HPA-5b and − 1b) differ significantly from those observed in neonatal alloimmune thrombocytopenia and post-transfusion purpura, where anti-HPA-1a is the most prevalent specificity. (2) Results for detection of HLA-antibodies differ considerably in relation to serological technique and target cells.