Objective   To explore the changes of apoptosis and expression of Fas and Fas-ligand(FasL)during acute rejection of limb allograft.

  Methods   Orthotopic limb allograft was performed on inbred SD rat and inbred Wistar rat.Experimental group: allogenic transplant group(SD Wistar), control group: (Wistar Wistar).The grafts were harvested on day 1, 3, 5, 7 after operation.All grafts samples were subjected to histologyical examination and electron microscopic examination.Apoptosis cells of grafts were monitored by terminal UTP nick-end labeling(TUNEL)method, and the Fas/FasL level detected by using immunohistochemistry method.

  Results   Histologically, mild, moderate and then severe acute rejection occurred gradually after operation in the experimental group.But none of control group had the histological evidence of acute rejection.The TUNEL showed that the number of apoptosis cells in the experimental group were significantly higher than that in the control.Apoptosis cells were mainly distributed in vascular endo thelial cells and basilar membrane cell of skin.Generally embolism in small vessels occurred due to severe rejection on the day 7 after operation.Fas/FasL expression in allografts were increased in correapondant with the degree of the apoptotic and histologyical damage.

  Conclusion   The Fas/FasL mediated apoptosis of vascular endothelial cells play an important role in acute rejection of limb allograft in rats, and might be an important parameter to evaluate the rejection and prognosis in the limb allograft.