HISTOPATHOLOGICAL FEATURES OF HEPATIC ALLOGRAFT REJECTION IN LIVING-RELATED LIVER TRANSPLANT RECIPIENTS

Abstract

191 Introduction: Living-related orthotopic liver transplantation(LRLT) has evolved to be a routine procedure over the past seven years in Japan. Since in most instances the donor is a parent, it is expected that the parent-child homology imparts an immunologic advantage against organ rejection. Minimized ischemia-reperfusion injury also may protect hepatic allograft rejection. However, the histopathological features of hepatic allograft rejection under LRLT are less clearly defined. Materials and Methods: A group of 37 consecutive patients who underwent LRLT at our institute between April 1995 and May 1997 was retrospectively studied. All patients primarily were administered FK506 with corticosteroids. Fifty-three liver needle biopsy specimens taken from 22 patients were available for this study. The biopsies were performed when the patients showed clinical or biochemical signs of graft dysfunction. Biopsy specimens were re-evaluated, and if the diagnosis of acute rejection was made, it was graded based on the Banff schema in 1995. Results: In the 37 patients the overall six months' survival rate was 75.7%. All patients had neither primary non function nor retransplantation. Twenty-one (56.8%) of 37 patients developed at least one episode of acute rejection. There were 49 episodes of rejection, and 33 were confirmed by biopsy. Sixteen episodes of acute rejection were diagnosed clinically and/or biochemically, and treated without biopsies. Thirty-four of 53 biopsy specimens had histological evidence of rejection; 14 mild, 14 moderate, 5 severe acute rejection, and one chronic rejection. Most of the portal inflammation was mild to moderate, and the venous endothelial inflammation was also mild except for five specimens that were diagnosed as severe acute rejection. However, there were large number of specimens that showed severe bile duct damage. Perivenular hepatocyte necrosis is observed in three specimens graded as severe. Only one patient who developed steroid-resistant acute rejection and chronic rejection received a course of muromonab-CD3. No graft was lost due to unresolved rejection. Four episodes of acute rejection were spontaneously resolved without additional immunosuppression. Of 31 cases that were followed more than one year after transplantation, although fourteen patients were weaned off steroids, histological severity did not correlate with steroid withdrawal. Conclusion: It is suggested that histological features of hepatic allograft rejection of LRLT are milder than those of cadaveric orthotopic liver transplantation reported by other groups, and the incidence of primary non function and chronic rejection were remarkably low.