Study On Immune Tolerance Induction In Rat Liver Transplantation By Pre-infusion Of 5-Fu Treated Allogeneic Lymphocytes

ObjectiveTo investigate the mechanism of immune tolerance induction in rat liver transplantation by pre-infusion of allogeneic lymphocytes treated with 5-Fu.Methods1. Wistar and SD rats were used as liver transplantation donors and recipients, respectively. And the model of rat orthotopic liver transplantation was established with two-cuff-technique.2. Wistar allogeneic lymphocytes were cultured in different concentrations in vitro.3. Animal were divided randomly into 4 groups as follows: Group A(n=10), take as control liver transplanted from Wistar to SD without any treatment; Group B(n=10), recipients were infused lymphocytes(5×10~6) from Wistar rat 7 days and 4 days separately before transplantation; Group C(n=10), recipients were infused 5-Fu(7.5ug/ml) treated allogeneic lymphocytes(5×10~6) from Wistar rat 7 days and 4 days separately before transplantation; Group D(n=10), recipients were infused 5-Fu(15ug/ml) treated allogeneic lymphocytes(5×10~6) from Wistar rat 7 days and 4 days separately before transplantation;4. Observations on post transplant clinical course. 7 days after liver transplantation, 4 recipients obtained form every group were killed to assess the acute rejection and the others were included in the survival analysis.5. The expression of FasL,CD4 and CD8 in the grafts were detected by immunohistochemical staining method. The Imag-pro Plus 6.0 software was used to analyze the images.Results1. Survival time of group C was 19.0±5.3d, longest than the other groups(P<0.05). There was no difference between group B(10.3±2.7d) and group D(11.7±3.9d), and survival time of group A(6.7±1.5d) was shortest(P<0.05).2. Pathologies: Mild acute rejection response was observated in the liver of group C. hepatic lobule existed and hepatocyte arranged neatly. central vein and header was invased by some inflammatory cells. group A showed serious acute rejection response, group B and D showed moderate rejection response. athological changes in group C was slighter than other groups.3. The expression of CD4 and CD8: In acini hepatis, the IOD SUM of CD8 in group A was higher than other groups(P<0.05). There were no significant difference in group C,group B and group D(P>0.05). In the header,the IOD SUM of CD8 in group A was higher than other groups(P<0.05), and the lowest in the group C. There were no significant difference between group B and group D. The expression of CD4 in the graft was negative.4. The expression of FasL:In the acini hepatis and header, the IOD SUM of FasL in group C was higher than other groups(P<0.05), and the lowest in the group A. There were no significant difference between group B and group D.Conclusion1. The model of orthotopic liver transplantation was established from Wistar to SD rats.2. In the acute rejection of rat liver allograft, CD8+T lymphocytes played a key role, while CD4+T lymphocytes was adjunctive.3. Pre-infusion of lymphocytes treated by low level 5-Fu can enhance the expression of FasL on recipient's liver cell after liver transplantation.4. The mechanism, that immune tolerance induction in rat liver transplantation by pre-infusion of allogeneic lymphocytes treated by 5-Fu, may be : induce the CD8+T lymphocytes in the graft apoptosis by the pathway Fas/FasL...