Successful treatment of ongoing intestinal allograft rejection permits recovery of graft structure and function.

Acute rejection episodes often complicate clinical small bowel transplantation, which prompted us to investigate whether such episodes can be reversed and the intestinal graft salvaged. Inbred Lewis rats that received fully allogeneic Brown-Norway small bowel allografts were treated with cyclosporin A (10 mg/kg) for 5 days, and the drug was then discontinued. Clinical and histologic signs of acute rejection developed, and the animals were subsequently treated with FK 506 (2 mg/kg) on days 14, 16, and 18. Survival was significantly prolonged (201.7 +/- 46.8 days) when compared with animals that were not administered FK 506 (16.5 +/- 0.8 days) or allograft recipients that received no immunosuppressive therapy (10.8 +/- 0.7 days). The histologic changes and functional impairment due to rejection that were observed prior to the start of the FK 506-therapy were reversed. However, biopsy specimens of all animals exhibited features of chronic rejection. This study provides evidence that acute rejection of intestinal allografts can be successfully treated with a short course of FK 506.