[Apoptosis of small intestinal epithelial cells in small intestinal allograft rejection]

To investigate apoptosis of epithelial cells during small intestinal allograft rejection in rats.

Heterotopic small intestinal transplantation was performed with inbred rat F344/N (RT1(l)) and inbred rat Wistar/A (RT1-A(k), RT1-E(d)). All recipients were divided into four groups: group I, nonoperative control (Wistar); group II, isograft control (Wistar-->Wistar); group III, allograft (F344-->Wistar); group IV, treatment control [F344-->Wistar + Cyclosporine A (6 mg x kg(-1) x d(-1))]. The grafts were harvested on day 3, 5, 7 after operation. All graft samples were subjected to histological examination and apoptotic cells of graft epithelial cells with terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL).

Histologically mild acute rejection occurred on day 3 after operation in group III, moderate acute rejection on day 5 after operation, severe acute rejection on day 7 after operation. But none of group II had the histological evidence of acute rejection and the histological evidence of group IV indicated that Cyclosporine A could effectively controlled small intestinal acute allograft rejection. The TUNEL showed that the number of apoptotic cells per crypt in group III was significantly higher than that of the other three control groups on day 3 and day 5 after operation (P < 0.01). The epithelial mucosa in group III completely sloughed on day 7 after operation.

Apoptosis plays an important role in small intestinal allograft rejection. Detection of apoptotic cells with TUNEL could be a valuable tool for the diagnosis of small intestinal allograft rejection.