HLA CLASS-I AND CLASS-II ANTIBODIES - MONITORING BEFORE AND AFTER KIDNEY-TRANSPLANTATION AND THEIR CLINICAL RELEVANCE

Background In search of an alternative screening technique, we compare d complement-dependent cytotoxicity (CDC) with PRA-STAT, a commerciall y available enzyme-linked immunosorbent assay (ELISA), Methods. A tota l of 188 pre- and posttransplant sera from 50 renal allograft recipien ts were tested with both methods, Results. A significant correlation w as found between both methods. Discrepant results could be explained b y the fact that PRA-STAT detects both HLA class I and II antibodies (w hile CDC with peripheral blood lymphocytes as target cell detects main ly HLA class I reactivity), by the presence of IgM antibodies (which a re not detected by the IgG specific ELISA test), and by CDC ''false-po sitive'' results due to antibody rejection treatment. The clinical rel evance of antibodies detected by PRA-STAT is suggested by the followin g. (a) In eight patients, donor-specific HLA antibodies detected by PR A-STAT (but not seen by CDC) resulted in severe rejection episodes, wh ich led to graft loss in four cases. In all but one patient, antibodie s were directed against class II or mixtures of class I and II antigen s, Six patients with complications were shown to have developed de nov o antibodies against DQ incompatibilities. (b) Half of the patients wi th a positive ELISA test at the moment of crossmatch experienced compl ications. Such patients are at a threefold higher risk of suffering fr om rejection episodes and/or graft loss than patients who are not sens itized (P<0.05, Fisher exact test), Conclusions, Because PRA-STAT is v ery reproducible, detects both HLA class I and II antibodies, and is n ot influenced by rejection therapy, we consider it an additional tool for pre- and posttransplant monitoring of kidney allograft recipients.