Autoimmune hepatitis: new paradigms in the pathogenesis, diagnosis, and management.

Autoimmune hepatitis (AIH), primary biliary cirrhosis, and primary sclerosing cholangitis are the three major autoimmune diseases affecting the liver, and of these three, AIH is the most typical autoimmune disease being characterized by a T-cell-rich infiltrate, raised circulating γ-globulins, autoantibodies, HLA associations, and links with other autoimmune diseases. It is the only one, of the three diseases, that responds well to immunosuppressive therapy. AIH is caused by dysregulation of immunoregulatory networks and the consequent emergence of autoreactive T cells that orchestrate a progressive destruction of hepatocytes leading untreated to liver failure. T cells play a major role in the immunopathogenesis, and both CD4(+) and CD8(+) T cells are involved together with effector responses mediated by NK cells, γδ T cells, and macrophages. A number of triggering factors have been proposed including viruses, xenobiotics, and drugs, but none have been conclusively shown to be involved in pathogenesis.