Induction of immune tolerance by pre-infusion of apoptotic lymphocytes derived from peripheral blood of donor rats before liver transplantation.

Acute rejection after liver transplantation is usually treated with large doses of immunosuppressants with severe toxic and side-effects, so it is imperative to find an effective method for preventing acute rejection. The aim of this study was to investigate the effects of immune tolerance by pre-infusion of apoptotic lymphocytes derived from peripheral blood of donor rats before liver transplantation. By using male Wistar and Sprague-Dawley (SD) rats as liver donors and recipients, an orthotopic liver transplantation model was established. The rats were divided into Group A (control group) and Group B (apoptotic lymphocytes pre-infusion group). In group B, 1ml apoptotic lymphocytes suspension (concentration 5×107 cells/mL) which were irradiated by X-ray from electron linear accelerator at the absorbed dose of 2.0Gy was pre-infused via the deep dorsal vein of penis on the 7th day before operation. The serum alanine transaminase (ALT), total bilirubin (TBIL), the serum of interleukin (IL) including IL-2, IL-4 and IL-10, liver pathological changes, and survival time were analysed. The survival in Group A were 7~13d, with the median survival time (MST) of 11d, and in Group B were 37~60 d, with the MST of 60 d. There were significant differences between the two groups in survival (P <0.001). There were significant differences between the two groups in ALT (P <0.01) and TBIL (P <0.01). Microscopic inspection revealed that severe acute rejection in the Group A, but no sign of acute rejection was observed in the Group B in the 7th day postoperation. The levels of IL-2 were increased after operation in two groups, but was obviously increased in the 7th (P <0.01) and 10th (P <0.001) day postoperation in Group A. The levels of IL-4 and IL-10 in Group A were declined but were increased in the 7th (P <0.01) and 10th (P <0.001) day postoperation in Group B. Preinfusion of apoptotic lymphocytes derived from peripheral blood of donor rats can induce immune tolerance in liver transplantation. Increased expression of Th2 cytokines (IL-4 and IL-10) may plays an important role in inducing immune tolerance.