Incidence of transfusion-induced platelet-reactive antibodies evaluated by specific assays for the detection of human leucocyte antigen and human platelet antigen antibodies

Background and Objectives The aim of this work was to study the incidence of transfusion-induced platelet-reactive antibodies in a selective patient population and evaluate different methodologies for platelet antibody screening (PAS). Materials and Methods The patients were retrospectively selected and divided into three separate groups: haematological malignancies (Group 1: n = 33); cardiac and orthopaedic patients (Group 2: n = 31) and a control group (Group 3: n = 23) selected with the same diagnoses of Group 2. PRE- and POST-transfusion samples were tested for PAS by the following tests: PIFT (platelet immunofluorescence test), MAIPA (monoclonal antibody immobilization of platelet antigen), Flow PRA (R) and LCT (lymphocytotoxicity test). Results There was not a 100% concordance among the methodologies used. PIFT, MAIPA and Flow PRA presented very similar results whereas that of LCT differed from the other methods. A high rate of positive results (32%) was found in the PRE samples followed by an increase of almost 50% after blood transfusion (POST samples: 42.5% of positivity), but there was a statistical difference (P < 0.05) between the PRE and POST transfusion sample only for the Flow PRA (R) technique tested on Group 2. Human leucocyte antigen (HLA) class I antibodies were present on 97.4% of POST positive samples, 5.4% presented anti-human platelet antigen (HPA)-1b antibodies and 8.1% presented a mix of panreactive antibodies against glycoprotein IIbIIIa, IaIIa and IbIX. Conclusions Blood transfusion did not increase the rate of alloimmunization in our haematological patients (Group 1); however, the patients were already admitted with a high rate of alloimmunization (12%). Group 2 patients are being immunized and the impact of this procedure remains to be studied as these patients may eventually undergo further hospitalization and receive more blood transfusion.