Screening for WBC antibodies by lymphocyte indirect immunofluorescence flow cytometry: superior to cytotoxicity and ELISA?

BACKGROUND: Cytotoxic WBC antibodies are found in patients who have refractoriness to platelet transfusion (RPT) or are experiencing febrile transfusion reactions (FTRs) and in sera giving so called nonspecific hemagglutination by IAT (N/S IAT). Sera from such patients were screened for WBC antibodies regardless of the ability to fix complement using a flow cytometric (FC) lymphocyte indirect immunofluorescence test (LIFT) to compare FC-LIFT with a routine lymphocytotoxicity test (LCT) for WBC antibody detection. STUDY DESIGN AND METHODS: Serum from 104 patients with RPT, 87 with FTR, and 147 with N/S IAT were tested in parallel by using FC-LIFT and LCT Sera giving discrepant results were re-tested with an HLA class I antibody ELISA to assess whether they were HLA-specific. RESULTS: Of the sera tested, 175 were LIFT positive, and 146 were LCT positive. Fifty-five had antibodies that were detectable only by LIFT; 26 were positive only by LCT. Of these 81 discrepant sera, 30 of 63 were positive in HLA ELISA. CONCLUSION: FC-Li FT detects more WBC antibodies than does LCT or ELISA, and it is a superior screening technique. Because some cytotoxic antibodies are detectable only by LCT, comprehensive WBC antibody screening would require the application of both techniques. However, because FC assessments of cytotoxicity have been described, LCTs may become redundant for WBC antibody screening.