A microplate ELISA for the detection of platelet alloantibodies: comparison with the platelet immunofluorescence test

An enzyme-linked immunoassay (ELISA) for the detection of platelet alloantibodies has been compared in detail with the platelet immunofluorescence test (PIFT). The ELISA appeared much simpler to perform than the PIFT. Both tests were comparable with regard to reproducibility and sensitivity. Alloantibodies were detected with ELISA and PIFT in 13 out of 14 patients who were refractory to random donor platelets. The value of these tests as a platelet crossmatch assay was determined in a retrospective comparison of the test results and the clinical transfusion responses expressed as the 1 h post-transfusion platelet recovery. 39/41 (95%) negative ELISA crossmatches and 30/33 (91%) negative PIFT crossmatches appeared to be associated with a successful platelet transfusion, whereas 7/10 positive ELISA crossmatches and 2/4 positive PIFT crossmatches appeared to be associated with transfusion failures. The high frequency of 'correct' negative tests indicates the importance of both assays in the prospective selection of compatible platelet donors for alloimmunized patients. However, because of its simplicity, the ELISA appears the method of choice for this purpose.