Immunological liver diseases in children.

Autoimmune liver diseases comprise a number of disorders in which inflammatory damage to the liver is believed to derive from an autoimmune attack. These include autoimmune hepatitis (AIH), characterised by positive smooth muscle and/or nuclear (SMA/ANA) or liver kidney microsomal type 1 (LKM1) antibodies, autoimmune sclerosing cholangitis (ASC), usually SMA/ANA positive, and AIH after liver transplantation, which is positive for SMA, ANA, or atypical LKM. These disorders often present with symptoms indistinguishable from prolonged acute hepatitis. Less commonly the onset is insidious, with nonspecific symptoms, or with complications of portal hypertension. For AIH and ASC, experimental evidence suggests that usually in individuals genetically predisposed to autoimmunity, a liver self antigenic peptide is recognized by T lymphocytes which promote a cascade of autoaggressive processes. For AIH after liver transplantation, the pathogenic mechanisms remain to be elucidated. All types of autoimmune liver disorders appear to respond favourably to early treatment with prednisolone with or without azathioprine. For patients presenting with fulminant hepatic failure or with already advanced cirrhosis, immunosuppression is rarely effective and the only mode of treatment is liver transplantation. The role of other immunosuppressant or immunomodulatory drugs, like cyclosporin A, tacrolimus or ursodeoxycholic acid, in the treatment of autoimmune liver disorders remains to be defined.