Immunoregulatory mechanisms in cyclosporine-treated renal allograft recipients

Cyclosporine (CsA)-treated recipients of a primary cadaveric (CAD) renal allograft were postoperatively evaluated for their donor and nonspecific immune responsiveness. Recipients with posttransplant (Tx) T helper (TH):T suppressor (TS) cell ratios less than 1.0 (averaged for the first 0-30 post-Tx days) had significantly better one-year serum creatinines (SCr) of 1.8 +/- 0.7 vs. 2.3 +/- 0.6 for recipients with TH:TS ratios greater than 1.0, P less than 0.05. Significantly fewer rejection episodes (30 vs. 57) and immune graft losses (10 vs. 19) were experienced by recipients with TH:TS ratios less than 1.0 vs. greater than 1.0, P less than 0.001 and 0.05, respectively. Recipients with TH:TS ratios less than 1.0 vs. greater than 1.0 displayed significantly lower post-Tx panel mixed lymphocyte culture (PMLC) stimulation indices (SI) of 24 +/- 11 vs. 38 +/- 6, P less than 0.05 and donor MLC SI of 15 +/- 6 vs. 31 +/- 8, P less than 0.05, respectively. Moreover, the post-Tx:pre-Tx donor MLC ratio of 0.58 +/- 0.2 vs. 1.1 +/- 0.32 was significantly lower in recipients with TH:TS ratios less than 1.0 vs. greater than 1.0, P less than 0.05. The suggested donor hyporesponsiveness in recipients with post-Tx TH:TS ratios less than 1.0 was further investigated by studying 46 CsA-treated allograft recipients for their ability to display regulatory T cell or adherent monocyte MLC suppressor activity. With a mean follow-up time of 5 +/- 4 months (range 0.5-14 months) we observed that 46% (21/46) of the patients displayed T cell suppressor activity, including 35% (16/46) with T-donor-specific and 46% (21/46) with T non-specific MLC suppressor activity. Additionally, 59% (27/46) of the patients also displayed nonspecific adherent monocyte MLC suppression. Recipients displaying either T cell or adherent monocyte suppression experienced significantly fewer rejection episodes than patients with no suppressor cell activity (P less than 0.05). Moreover, patients with T cell suppressor activity displayed a significantly lower panel and donor MLC vs. patients not displaying T suppressor activity (P less than 0.05. and 0.05, respectively). Finally, there was a significant correlation between the display of T cell suppressor activity in patients who were matched with their donors at the HLA-DR locus vs. no display of T suppressor activity in those patients unmatched with their donors at the HLA-DR locus.