Abstract: Objective To research the degree of immune graft rejection, the quantity and function of regulatory T cells in the model of liver transplantation after mice liver transplantation to provide theory evidence in revealing mechanisms of immune tolerance. Method Transplantation liver samples were collected at 3d, 7d, 14d, 28d after allogeneic or syngeneic mice liver transplantation (N=4 for each group at one time point). Graft rejection score was given with HE staining. T and B lymphocytes and change of regulatory T cells were identified with IHC staining.The change of Foxp3 mRNA and CLAT-4 on surface of regulatory T cells were detected by real-time PCR and IFC respectively. Results Allogeneic graft was rejected during 2w after transplantation, and the rejection receded generally after 2w. Inflammatory cells intra-graft was mainly T lymphocytes. Foxp3 positive cells and mRNA of Foxp3 in allogeneic graft group was significantly higher than these in isogeneic graft group (15.0+1.3 vs. 2.7+1.0，P<0.05）. Meanwhile, expression of CLAT-4 on regulatory T cells also was higher in allogeneic graft group compared with isogeneic graft group(53%+3% vs. 13%+2%,P<0.05). Conclusion The immunity rejection after allogeneic liver transplantation achieved by regulatory T cells negative regulation and then achieved immune tolerance.

Key words: mice，liver transplantation，immune tolerance，regulatory T cells