Objective:To investigate the relationship between ischemic preconditioning (IP) and acute rejection (AR) after allogenic orthotopic liver transplantation (OLT) in rats.
Methods:By using random digits table,the rats were divided into Sham group (group A), similar gene OLT group (group B), OLT with ischemia reperfusion (IR) group (group C, D), and ischemic OLT with IR and with or without IP group(group E, F).  The rats were killed at 1，3，5 and 7 day after the models and sham operation were constructed respectively. Plasma samples were assessed for the severity of IR injury (IRI). The liver tissue was paraffin-embedded to examine the liver histological changes (HE), and rejection was classificed by rejection activity index of Banff. Apoptosis was measured by TUNEL, and the protein and mRNA expression of Fas, perforin and granzyme B were detected by using immunohistochemistry and real-time PCR.
Results:The severity of acute rejection in hepatic tissue of groups C-F was paralleled with the degree of IRI.No rejection occurred in group A and B. The extent of disease and degree IRI and the classification of rejection activity index were lower in group E than in group  C, and group F than group D (P＜0.05). The mRNA and protein expression levels of Fas, perforin and granzyme B in group C were higher than group  E (P＜0.05),  and group  D were higher than group F (P＜0.05) at 1，3，5 and 7 days after graft reperfusion.
Conclusions: IP relieved the severity of IRI and the classification of acute rejection of the same cold and warm ischemia time, which is correlated with modulation of apoptosis and modulation of mRNA and protein expression of Fas, perforin and granzyme B.