Autoimmune hepatitis (AIH) is an inflammatory liver disease caused by the immune system mistakenly attacking the cells of the liver. It can be found in anyone at any age, but about 80% of those affected are women.
Autoimmune hepatitis is not the direct result of other causes such as a viral infection, drug, toxin, hereditary disorder, or alcohol abuse. It can lead to liver cirrhosis and, in some cases, to liver failure. The diagnosis of autoimmune hepatitis is best achieved with a combination of clinical, laboratory and histological findings.
The disease is characterised by interface hepatitis, elevated transaminase levels, and serologically by the presence of autoantibodies and increased immunoglobulin gamma levels. Overlap syndrome with primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) has been observed. AIH responds to immunosuppressive treatment, which should be instituted as soon as the diagnosis is made.
There are several subtypes of AIH recognised, but the clinical utility of distinguishing subtypes is limited. AIH type 1 affects predominantly adults while 80% of patients with AIH type 2 are children. Seropositivity for ANA and/or ASMA defines AIH type 1, positivity for LKM-1 antibodies and/or LC-1 antibodies indicate AIH type 2. AIH type 2 patients with LC-1 antibodies have histologically more severe disease compared to those without anti-LC-1 antibodies.
SLA antibodies are proposed as specific markers of a third type of severe AIH (AIH type 3) seronegative for the conventional AIH type 1 autoantibodies. Similarities in the clinical profile between patients with AIH type 1 (positive for ANA and/or ASMA) and AIH patients with SLA/LP antibodies alone suggest that anti-SLA is rather an additional important marker for the diagnosis of AIH type 1, than a marker of a third type of AIH. Anti-SLA antibodies denote patients with a more severe course of AIH and a propensity for relapse after corticosteroid withdrawal compared to their negative counterparts.