FALSE-NEGATIVE RESULTS IN ANTI-HLA ANTIBODY DETECTION BY SANGSTAT-ELISA - COMPLEMENT-DEPENDENT CYTOTOXICITY IS NOT YET OBSOLETE

Although ELISA on purified HLA molecules for detecting anti-HLA antibo dy (P-S ELISA) does detect some antibodies previously missed by the co nventional complement dependent cytotoxicity method (C Cytotox), HLA E LISA should not fail to detect antibodies already detected by the conv entional reference method to be able to make C Cytotox obsolete and to replace it in routine testing. Among 40 selected sera, 8 false-negati ve reactions were observed in P-S ELISA. These sera were reanalyzed bl ind in two laboratories and found to contain non-IgM, warm anti-HLA an tibodies. These antibodies were directed in 4 cases against an HLA mol ecule expressed on a kidney transplant previously rejected by the subj ect. These antibodies, if missed, would have been potentially harmful in kidney transplantation. Thus P-S ELISA can't yet replace C Cytotox in routine anti-HLA class I detection. The cost/benefit ratio of P-S E LISA as a second-line test remains to be investigated.