Abstract:Objective:To study apoptosis of small bowel epithelial cells during rejection of small bowel grafts and explore the correlation between apoptosis and cytokine(Interleukin-1β). Methods:Heterotopic small intestinal transplantation was performed in SD and Wistar rats. All recipients were divided into three groups: Group I isograft(SD-SD);Group II allograft(Wistar-SD);Group III treatment control(Wistar -SD treated with cyclosporine A). The grafts were harvested on day 1, 3, 5, 7 after operation. All graft samples were examined for apoptotic cells of graft epithelial cells with TUNEL method. Serum IL-1β levels were detected by sandwich ELISA method. Results:The TUNEL method showed that in Wistar→SD group, apoptosis of intestinal mucosa epithelial cells occurred during mild, moderate and severe rejection, and the number of apoptotic cells increased with increase of severity of rejection(P<0.01), and was significantly higher than in SD→SD group(P<0.01). The number of apoptotic cells was also increased in Wistar→SD+CsA group(P<0.01). Rejection was mild in SD→SD group, and the number of apoptotic cells was not significantly changed(P>0.05). ELISA method showed no significant change of serum IL-1β in SD→SD group(P>0.05), but in Wistar→SD group and Wistar→SD+CsA group, the serum IL-1β levels increased as the number of apoptotic cells increased(P<0.01). Increase in level of IL-1β and increase in number of apoptotic cells showed a significant positive correlation(r=0.798, P<0.01). Conclusions: Apototic phenomena are present during rejection of small intestinal graft. IL-1β can promote the development of cell apoptosis.