Detection and Identification of Platelet-Associated Alloantibodies by a Solid-Phase Modified Antigen Capture Elisa (MACE) Technique and Its Correlation to Platelet Refractoriness in Multi platelet Concentrate Transfused Patients.

Platelets express glycoproteins (IIb/IIIa, Ib/IX, Ia/IIa, IV, and HLA-1) that are polymorphic and can become targets for antibody responses. Patients at threat are those who received multiple platelet transfusions. Modified antigen capture elisa (MACE) is a qualitative solid phase Elisa designed to detect IgG antibodies against platelet specific antigens. The study has been carried out over a period of 2 years. A total of 100 patients were selected, who had been transfused with at least 15 units of platelet concentrate. All patients were having either hematological malignancies or bone marrow failure syndromes. Platelet antibodies were identified using MACE-1&2. Data was analysed statistically, using odds ratio (OR) with 95 % confidence interval. 39 % of the patients were found to be alloimmunized against platelet antigens, of which eleven showed refractoriness. Six patients (54.5 %) with HLA-1, two patients (9.5 %) with GPIb/IX, two patients (40 %) with both HLA-1 and GPIIb/IIIa, and one patient with GPIIb/IIIa antibodies showed refractoriness. Production of HLA-1 antibody and the development of refractoriness was found to be significant with OR 14.05 and P value 0.0025. MACE-1&2 enabled specific detection and identification of platelet antibodies, which in turn correlated well with the development of refractoriness in multi transfused patients. GPIb/IX was detected as the commonest antibody in our patient population, which is in variance with Europian studies where it is GPIa/IIIa (HPA-1a/5b). This technique should be utilised in patients who are at an increased risk of developing alloimmunisation due to repeated platelet transfusions.