Protein F-induced immune tolerance in liver transplantation in rats

Liver-specific protein F is commonly used in liver transplantation studies for its allograft immunogenicity. The objective of this study was to investigate immune tolerance induced by protein F in liver transplantation in rats. Healthy inbred male Wistar and Sprague-Dawley (SD) rats were used in this study. The transplant recipient rats were randomly divided into three groups. The SD rats transplanted with liver tissues from SD rats or Wistar rats were defined as intragraft control group (Group A) or acute reaction group (Group B), respectively. The SD rats that received thymic administration of 4 mg protein F 1 week prior to transplantation with livers from Wistar rats were defined as protein F interference group (Group C). Kamada's two-cuff technique was utilized in the liver transplantation surgeries. The postoperative general condition, transplantation survival time, pathological examination, and serum IFN-γ level (quantified by ELISA) were recorded and compared to evaluate the immune response and outcomes in the recipient rats after liver transplantation. Group A rats exhibited good postoperative condition and prolonged survival (median survival time was 92 days). In contrast, Group B rats lost body weight rapidly after liver transplantation, and died starting at day 12 (median survival time was 15 days). Compared to Group B, Group C rats showed significantly longer survival (medium survival time was 71 days). Our findings indicate that protein F is an important transplantation antigen with allograft immunogenicity, which could successfully induce immune tolerance in liver transplantation.