Autoimmune hepatitis

Autoimmune Hepatitis is a disease of the liver that occurs when the body's immune system attacks cells of the liver. Anomalous presentation of human leukocyte antigen (HLA) class II on the surface of hepatocytes, possibly due to genetic predisposition or acute liver infection, causes a cell-mediated immune response against the body's own liver, resulting in autoimmune hepatitis. This abnormal immune response results in inflammation of the liver, which can lead to further complications, including cirrhosis.

Autoimmune hepatitis has an incidence of 1-2 per 100,000 per year, and a prevalence of 10-20/100,000. As with most other autoimmune diseases, it affects women much more often than men (70%). Liver enzymes are elevated, as may be bilirubin.

Classification
Four subtypes are recognised, but the clinical utility of distinguishing subtypes is limited.


 * 1) positive ANA and SMA, raised immunoglobulin G (classic form, responds well to low dose steroids);
 * 2) positive LKM-1 (typically female children and teenagers; disease can be severe), LKM-2 or LKM-3;
 * 3) positive antibodies against soluble liver antigen (this group behaves like group 1) (anti-SLA, anti-LP)
 * 4) no autoantibodies detected (~20%)

Diagnosis
The diagnosis of autoimmune hepatitis is best achieved with a combination of clinical, laboratory and histological findings.

A number of specific antibodies found in the blood (antinuclear antibody (ANA), anti-Smooth Muscle Antibody (SMA), liver/kidney microsomal antibody (LKM-1, LKM-2, LKM-3), anti soluble liver antigen (SLA/LP) and anti-mitochondrial antibody (AMA)) are of use, as is finding an increased Immunoglobulin G level. However, the diagnosis of autoimmune hepatitis always requires a liver biopsy.

In complex cases, a scoring system can be used to help determine if a patient has autoimmune hepatitis, which combines clinical and laboratory features of a given case.

Overlapping presentation with primary biliary cirrhosis and primary sclerosing cholangitis has been observed.

Treatment
Treatment is with glucocorticoids with or without azathioprine and remission can be achieved in up to 60–80% of cases, although many will eventually experience a relapse. Patients who do not respond to glucocorticoids and azathioprine may be given other immunosuppressives like cyclosporin, tacrolimus, methotrexate etc. Liver transplantation may be required if patients do not respond to drug therapy or when patients present with fulminant liver failure.