Delayed acute rejection episodes in cyclosporine-treated renal transplant recipients.

Of 109 cyclosporine-treated cadaveric renal allograft recipients, 45 were free of acute rejection in the first 4 weeks after transplantation. Eleven of 45 (24%) subsequently had delayed, biopsy-proven first rejection episodes 34-61 days after grafting, often after discharge from the hospital. Delayed rejectors had significantly higher plasma creatinine levels at all times during the first posttransplant month than 34 nonrejectors. Trough serum cyclosporine levels were similar in the two groups, although by the 4th week oral cyclosporine dose was significantly lower in the delayed rejection group. Two-thirds of those patients who had serum creatinine levels greater than or equal to 260 mumol/l at 2 weeks and greater than or equal to 225 mumol/l at 3 weeks had a delayed acute rejection episode. Renal transplant recipients treated with cyclosporine who have serum creatinine levels at or above these levels should be aggressively worked up and closely followed for the development of delayed acute rejection.