Detection of platelet antibodies using a micro-enzyme-linked immunosorbent assay (ELISA).

An enzyme-linked immunosorbent assay (ELISA) for the measurement of circulating platelet antibody and platelet-associated IgG (PAIgG) is described. The test is done in microtiter plates and rapidly provides quantitative and highly reproducible results. Alloantibodies from 28 of 30 multiple transfused patients and isoantibodies from 3 of 4 patients with immune thrombocytopenic purpura (ITP) were detected. PAIgG was elevated in all 4 patients with ITP, and HLA and platelet-specific antigens were reliably detected using HLA typing sera and anti-PIA1 antibody, respectively. Platelets preserved wither by dessication in the wells of the microtiter plates or in liquid suspension in saline at 4 degrees C gave results comparable to values using fresh platelets. Storage periods ranged from 30 days for dessicated platelets to more than 1 yr for platelets stored in suspension. The ability to utilize preserved platelets may allow relatively convenient screening of large numbers of potential platelet donors for alloimmunized patients.