['To investigate the effect and mechanism of FTY720 on acute graft versus host disease (GVHD) in rat small bowel transplantation (SBTx).', 'Heterotopic SBTx was performed using a parent (WF)-into-F1 (WFxACI) rat combination. Recipient rats were divided into experimental group (n=6) and control group (n=6). Rats in the experimental group were administered with FTY720 at 0.5 mg/kg for 14 days. Lymphocyte apoptosis in the liver and the mucosa of intestine and graft was detected by TUNEL and flow cytometry 15 days after transplantation. Recipient survival and lymphocyte apoptosis were compared between the two groups.', 'Recipients in the control group died of GVHD after a mean survival time of (16+/-2.1) days. FTY720-treated recipients had a significantly longer survival (>100 days). After administration of FTY720, the percentage of apoptotic lymphocytes was significantly increased in the graft as compared to that in the control group by flow cytometry. The ratio of apoptotic lymphocyte in the liver and graft was also significantly higher in the experimental group by TUNEL.'] Does [ FTY720-induced lymphocyte apoptosis inhibit acute graft versus host disease in rat small bowel transplantation ]?