DETECTION AND CLINICAL SIGNIFICANCE OF LYMPHOCYTOTOXIC ANTIBODIES FOLLOWING RENAL TRANSPLANTATION.
          Torrecilhas ACT, Moura LAR, Medina JOP, Panajotopoulos N, Gerbase-DeLima M.   Department of Pediatrics, Escola Paulista de Medicina, UNIFESP, São Paulo, S.P, Brazil.
          It has been suggested that the development of lymphocytotoxic antibodies (Ab) after renal transplantation is associated with a poor prognosis. However, the prevalence and the clinical significance of this event are not yet well defined. In the present study we have analyzed panel reactive antibodies (PRA) in the sera of 47 renal transplant (Tx) recipients (R). A pre-Tx and 5 post-Tx (7, 14, 30, 60, 90 days) serum samples, with (DTT-serum) and without DTT treatment, were simultaneously tested against 25 selected cells using the NIH and polyethylene glycol-enhanced (PEG) cytotoxicity techniques. A PRA variance greater than 10 percentual points above the pre-Tx PRA was considered as post-Tx Ab production. Among the 7 R of HLA-identical grafts, 14% and 43% showed an increased NIH-PRA and PEG-PRA, respectively, when non-DTT-sera were tested, whereas none of them presented any increase in PRA when DTT-sera were assayed. Among the 40 R of non-HLA-identical grafts, 63% (NIH-PRA) and 88% (PEG-PRA) showed an increased PRA in non-DTT-sera, whereas with DTT-sera a PRA increase was observed in 23% of the R, considering the NIH-PRA, and in 28% of the R, considering the PEG-PRA. Regarding the association with rejection episodes in these 40 R, no relationship was found with increased PRA in non-DTT-sera. In contrast, there was a significant association between IgG production (PRA with DTT-sera) and rejection. Among the 9 R who had an increased NIH-PRA, 88% presented rejection episodes, and among the 11 R who had an increased PEG-PRA, 91% had rejection episodes. On the other hand, among the 31 R who did not show an increased NIH-PRA, 32% had rejection episodes, and among the 29 R who did not show an increased PEG-PRA, 31% presented rejection episodes. In conclusion, the post-Tx increase in PRA of DTT-serum seems to be a sensitive marker for rejection, although its specificity is rather low, at least considering any kind of acute rejection.