Analysis of a high-throughput HLA antibody screening assay for use with platelet donors

BACKGROUND: Passive infusion of HLA antibodies has been implicated in transfusion reactions. A rapid, inexpensive method of screening blood donors for HLA antibodies might reduce the incidence of reactions. A high-throughput microbead-flow analyzer HLA antibody detection technique was compared with an enzyme-linked immunosorbent assay (ELISA) method. STUDY DESIGN AND METHODS: Ninety-six apheresis platelet (PLT) donors were tested for antibodies to Class I and II HLA antigens with mixed-antigen microbead-flow analyzer and ELISAs. For both assays, samples reactive in the mixed-antigen assay were tested with a panel-reactive antibody (PRA) assay. Samples reactive in both the mixed-antigen and the PRA assays were considered positive. RESULTS: In the mixed-antigen microbead assay, 46 (48%) samples were reactive to Class I antigens and 20 (21%) to Class II. Further testing in the microbead PRA assay revealed that 34 (35%) had antibodies to Class I antigens, 18 (19%) to Class II, and 42 (44%) to either Class I or Class II. Class I antibodies were present in 56 percent of females and 36 percent of males. In the mixed-antigen ELISA, 4 samples were reactive with Class I antigens, 4 with Class II antigens, and 5 with Class I or Class II. All 5 reactive samples were also reactive in the ELISA PRA assay and were from females. CONCLUSION: The microbead assay was more sensitive than the ELISA and detected antibodies in a large proportion of donors. Samples reactive in the mixed-antigen microbead assay should be confirmed by a second assay before concluding that antibodies are present.