ABSTRACT
BACKGROUND: We studied the incidence of platelet alloimmunization in multitransfused patients with haemato-oncological disorders and determined the factors influencing alloimmunization. We also assessed the effect of alloimmunization on response to platelet transfusion. METHODS: Fifty patients with haemato-oncological disorders who received multiple transfusions were included. The patients were tested for antibodies before they received any transfusion and then after 3-4 weeks of transfusion. Lymphocytotoxicity and platelet immunofluorescence suspension tests were used to detect antiplatelet antibodies. Symptomatic improvement was used to assess the response to platelet transfusions. RESULTS: Thirty patients were positive by the lymphocytotoxicity test, giving an incidence of 60% for anti-HLA antibodies. The panel reactivity of the antibodies ranged from 3% to 100%. Nineteen patients were positive by the platelet immunofluorescence suspension test, 16 of whom were also positive by the lymphocytotoxicity test. The overall incidence of antiplatelet antibodies was 66%. The number of transfusions received and the underlying haemato-oncological disorder were not risk factors for the development of antibodies. Patients with a past history of transfusions and those with a positive obstetric history had a significantly higher incidence of antibodies. The response to transfusion therapy was poor in patients with antibodies, as 71.4% of patients with antibodies were nonresponsive compared to only 26.6% of antibody-negative patients. CONCLUSION: A high percentage of multitransfused patients developed antiplatelet antibodies. Previous sensitization was an important risk factor for the development of antibodies. Patients with high panel reactivity (HLA) showed non-responsiveness to platelet transfusions. Testing for the presence of antiplatelet antibodies and provision of compatible platelets should be important components in the management of patients with platelet transfusion refractoriness.