Comparison of crossmatch results obtained by ELISA, flow cytometry, and conventional methodologies

The complement-dependent lymphocytotoxicity crossmatch (CXM) is the present ly accepted standard for detection of donor-reactive alloantibodies in tran splant patients. However, the newer flow cytometric (FXM) and ELISA (EXM) c rossmatch technologies are increasingly used as substitutes for the CXM. We have compared the sensitivity and reproducibility of FXM vs. EXM and, in g eneral, find them to be quite similar. However, when we compared the agreem ent of FXM vs. EXM in 112 donor/recipient combinations, we found that they identified different subsets of donor-specific alloantibodies in about 35% of the tests. When compared to the standard CXM method, the EXM correlated much better than did the FXM, yielding a much lower rate of false positive (2.5% vs. 8%) and false negative (7% vs. 18.5%) results. The reduction in t ime required to obtain a result (3 h) and the cost of materials ($25/test) was identical for the EXM and FXM. We conclude that the ELISA method for cr ossmatching has advantages over the flow cytometric method as a substitute for the present standard complement-dependent lymphocytotoxicity method. (C ) American Society for Histocompatibility and Immunogenetics, 1999. Publish ed by Elsevier Science Inc.