Autoimmune hepatitis Autoimmune hepatitis is a disease of immune-mediated liver injury characterised by the presence of serum antibodies and peripheral blood T lymphocytes reactive with self-proteins, a strong association with other autoimmune diseases , and high levels of serum immunoglobulins - in paicular, elevation of IgG. Although most commonly seen in women, paicularly in the second and third decades of life, it can develop in either sex at any age. The reasons for the breakdown in immune tolerance in autoimmune hepatitis remain unclear, although cross-reactivity with viruses such as HAV and EBV in immunogenetically susceptible individuals (typically those with human leucocyte antigen (HLA)-DR3 and DR4, paicularly HLA-DRB3*0101 and HLA-DRB1*0401) has been suggested as a mechanism. Pathophysiology Several subtypes of this disorder have been proposed that have differing immunological markers. Although the different patterns can be associated with variation in disease aspects, such as response to immunosuppressive therapy, histological patterns are similar in the different settings and the basic approach to treatment (complete control of liver injury using immunosuppressive drugs and maintained with appropriate therapy) is the same. The formal classification into disease types has fallen out of our in recent years. The most frequently seen autoantibody pattern is high titre of antinuclear and anti-smooth muscle antibodies, typically associated with IgG hyperglobulinaemia (type I autoimmune hepatitis in the old classification), frequently seen in young adult females. Disease characterised by the presence of anti-liver-kidney microsomal (LKM) antibodies, recognising cytochrome P450-IID6 expressed on the hepatocyte membrane, is typically seen in paediatric populations and can be more resistant to treatment than ANA-positive disease. Adult onset of anti-LKM can be seen in chronic HCV infection. This was classified as type II disease in the old system. More recently, a pattern of antibody reactivity with anti-soluble liver antigen (anti-SLA) has been described in typically adult patients, often with aggressive disease and usually lacking autoantibodies of other specificities. Clinical features The onset is usually insidious, with fatigue, anorexia and eventually jaundice. The non-specific nature of the early features can lead to the diagnosis being missed in the early disease stages. In about one-quaer of patients the onset is acute, resembling viral hepatitis, but resolution does not occur. This acute presentation can lead to extensive liver necrosis and liver failure. Other features include fever, ahralgia, vitiligo and epistaxis. Amenorrhoea can occur. Jaundice is mild to moderate or occasionally absent, but signs of chronic liver disease, especially spider naevi and hepatosplenomegaly, can be present. Associated autoimmune disease, such as Hashimoto's thyroiditis or rheumatoid ahritis, is often present and can modulate the clinical presentation. Ref Davidson edition23rd pg 886