Correlation of histology to clinical rejection reversal: A Thymoglobulin Multicenter Trial report

Background. Histology may provide a link between clinical response to antirejection therapy and graft function. In a subset of centers, renal biopsy was a secondary end point for the Thymoglobulin Multicenter Trial. Methods. Thirty-eight patients had a protocol biopsy one to two weeks following the end of therapy. Inclusion and posttreatment biopsies were graded and scored according to Banff criteria by a central pathologist who was blinded to the type and outcome of therapy and the timing of the biopsy. Results. The majority of patients (31 of 38) had moderate rejection on their inclusion biopsy. An improvement of at least one Banff grade occurred in 58% of the patients. The treatment was clinically successful in 33 patients, but two thirds of the patients (25 out of 38) demonstrated residual inflammation in the graft. The degree of improvement of inflammation was proportionate to rejection severity (P = 0.006). Banff scoring indicated that residual inflammation was less in Thymoglobulin-treated patients than in those receiving Atgam (P < 0.05) and correlated with the incidence of recurrent rejection (P = 0.015). Conclusions. These data demonstrate a discrepancy between clinical and histological resolution of acute renal allograft rejection. Residual infiltrates in the graft following rejection therapy are common and, despite clinical improvement, may indicate an increased risk for recurrent rejection.