SERIAL POST TRANSPLANT IMMUNE MONITORING OF ANTI-HLA ANTIBODY.
RH Kerman, SM Katz, CT Van Buren, JA Ruth, E McKissick, S Rasmussen, BD Kahan, Univ. of Texas Medical School - Houston

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Although the presence of anti-HLA antibodies in renal transplant (Tx) recipient sera has been associated with graft rejection and/or loss, the role of these antibodies is not well understood. A reliable test that monitors serologic anti-HLA reactivity might identify patients at risk for rejection. We used an ELISA-based assay to detect IgG anti-HLA class I and class II antibodies bound to soluble HLA target antigens. Sera were collected pre and monthly post-Tx for 19 ± 8 months (15 sera/patient average) from 123 CsA-Pred treated primary recipients of a cadaveric donor renal allograft. The rejection frequency of 73% for patients with pre-Tx ELISA detected IgG anti-HLA PRA > 10% was significantly greater than the 27% rejection frequency for patients with pre-Tx PRA <10% (73% vs 27%, p<0.01). Post-operatively, one-third of the patients did not develop ELISA-detectable anti-HLA antibodies, had no rejections, had a 90% one-year graft survival and experienced an 8% frequency of chronic rejection. In contrast, the 67% of the patients with ELISA detectable IgG anti-HLA experienced a 79% one year graft survival (90% vs 79%, p<0.02), and a 26% frequency of chronic rejection from one to three years post-Tx (8% vs 26%, p<0.02). There was a significantly consistent monthly ELISA-detected IgG anti-HLA PRA > 10% present in sera 3 ± 4 months prior to the diagnosis of chronic rejection, but not for non-rejectors (71% vs 18%, p<0.02). Our data suggest that serial monitoring of IgG anti-HLA antibody may identify recipients at risk for acute and/or chronic rejection.