Immune cholangitis: liver allograft rejection and graft-versus-host disease.

A pronounced similarity exists between liver allograft rejection and graft-versus-host disease (GVHD) in the damage and eventual destruction of small intrahepatic bile ducts. Although an immunologic reaction has an important role, precisely identifying the target antigens or reason for persistence of the immune response has been difficult. An important difference between GVHD and liver rejection is the development of obliterative arteriopathy only in rejection. The three main histopathologic features of acute rejection are a predominantly mononuclear but mixed portal inflammation, subendothelial inflammation of portal or terminal hepatic veins (or both), and bile duct inflammation and damage. In acute rejection, a controversial issue is determining when therapeutic intervention is needed. The recommended approach is to base treatment on a combination of histopathologic changes and liver injury or dysfunction. Chronic rejection, which usually does not occur before 2 months after transplantation, is characterized by two main histopathologic features: (1) damage and loss of small bile ducts and (2) obliterative arteriopathy. Acute GVHD begins within the first month after transplantation and most commonly involves the skin, gastrointestinal tract, and liver, whereas chronic GVHD usually develops more than 80 to 100 days after liver transplantation and affects 30 to 50% of long-term survivors. Recognition of the early, cellular stages of chronic GVHD is important in preventing irreversible damage.