SOLUBLE HLA ANTIGENS AND ELISA - A NEW TECHNOLOGY FOR CROSS-MATCH TESTING

A soluble HLA ELISA for the detection of donor specific anti-HLA class I IgG antibodies was developed and compared with microlymphocytotoxic ity. Donor sHLA was prepared from donor blood or purified blood lympho cytes and captured onto monoclonal antibody coated ELISA plates. After incubation of captured HLA with test serum, bound IgG antibodies were detected using a peroxidase-conjugated anti-human IgG antibody. Serum samples from patients on waiting lists to receive kidney transplants were tested by lymphocytotoxicity (AHG protocol) and/or sHLA ELISA in four different laboratories using HLA preparations from eight organ do nors. Concordant crossmatch results were obtained for 854 (99%) of 864 ELISA crossmatches. In contrast, concordant results were obtained for 234 (91%) of 256 lymphocytotoxicity crossmatches. Interlaboratory rep roducibility of ELISA results was 99%. In contrast, interlaboratory re producibility of lymphocytotoxicity assay results was 78%. Endpoint ti trations of serum specimens containing anti-HLA antibodies demonstrate d equivalent sensitivity of ELISA and AHG lymphocytotoxicity crossmatc h and similar sensitivity of ELISA and flow cytometry crossmatch. Spec imens tested positive by lymphocytotoxicity without DTT treatment but negative with DTT treatment were tested negative by ELISA, Comparison of lymphocytotoxicity and ELISA crossmatch results showed an agreement of 94%. This demonstrates that detection of anti- donor HLA class I a ntibodies by ELISA is a reliable alternative to microlymphocytotoxicit y testing.