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

Human leukocyte antigen

The human leukocyte antigen system is the name of the major histocompatibility complex in humans. The super locus contains a large number of genes related to immune system function in humans. This group of genes resides on chromosome 6, and encodes cell-surface antigen-presenting proteins and...

 (HLA) class II on the surface of hepatocyte

Hepatocyte

A hepatocyte is a cell of the main tissue of the liver. Hepatocytes make up 70-80% of the liver's cytoplasmic mass.These cells are involved in:* Protein synthesis* Protein storage* Transformation of carbohydrates...

s, possibly due to gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

tic predisposition or acute

Acute (medicine)

In medicine, an acute disease is a disease with either or both of:# a rapid onset, as in acute infection# a short course ....

 liver

Liver

The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...

 infection

Infection

An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...

, 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

Cirrhosis

Cirrhosis is a consequence of chronic liver disease characterized by replacement of liver tissue by fibrosis, scar tissue and regenerative nodules , leading to loss of liver function...

.

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 disease

Autoimmune disease

Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body. In other words, the body actually attacks its own cells. The immune system mistakes some part of the body as a pathogen and attacks it. This may be restricted to...

s, it affects women much more often than men (70%). Liver enzymes are elevated, as may be bilirubin

Bilirubin

Bilirubin is the yellow breakdown product of normal heme catabolism. Heme is found in hemoglobin, a principal component of red blood cells. Bilirubin is excreted in bile and urine, and elevated levels may indicate certain diseases...

.

Classification

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

1. positive ANA and SMA, raised immunoglobulin G
   Immunoglobulin G
   Immunoglobulin G are antibody molecules. Each IgG is composed of four peptide chains — two heavy chains γ and two light chains. Each IgG has two antigen binding sites. Other immunoglobulins may be described in terms of polymers with the IgG structure considered the monomer.IgG constitutes 75%...
   
    (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

Medical diagnosis

Medical diagnosis refers both to the process of attempting to determine or identify a possible disease or disorder , and to the opinion reached by this process...

 of autoimmune hepatitis is best achieved with a combination of clinical

Clinical trial

Clinical trials are a set of procedures in medical research and drug development that are conducted to allow safety and efficacy data to be collected for health interventions...

, laboratory

Laboratory

A laboratory is a facility that provides controlled conditions in which scientific research, experiments, and measurement may be performed. The title of laboratory is also used for certain other facilities where the processes or equipment used are similar to those in scientific laboratories...

 and histological findings.

A number of specific antibodies found in the blood (antinuclear antibody (ANA), anti-Smooth Muscle Antibody

Anti-smooth muscle antibody

Anti-smooth muscle antibodies are antibodies formed against smooth muscle. These antibodies are typically associated with autoimmune hepatitis.These antibodies can be directed against actin, troponin, and tropomyosin....

 (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

Liver biopsy

Liver biopsy is the biopsy from the liver. It is a medical test that is done to aid diagnosis of liver disease, to assess the severity of known liver disease, and to monitor the progress of treatment.-History:...

.

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

Primary biliary cirrhosis

Primary biliary cirrhosis, often abbreviated PBC, is an autoimmune disease of the liver marked by the slow progressive destruction of the small bile ducts within the liver. When these ducts are damaged, bile builds up in the liver and over time damages the tissue. This can lead to scarring,...

 and primary sclerosing cholangitis

Primary sclerosing cholangitis

Primary sclerosing cholangitis is a chronic liver disease caused by progressive inflammation and scarring of the bile ducts of the liver. The inflammation impedes the flow of bile to the gut, which can ultimately lead to liver cirrhosis, liver failure and liver cancer...

 has been observed.

Treatment

Treatment is with glucocorticoids with or without azathioprine

Azathioprine

Azathioprine is a purine analogue immunosuppressive drug. It is used to prevent organ rejection following organ transplantation and to treat a vast array of autoimmune diseases, including rheumatoid arthritis, pemphigus, inflammatory bowel disease , multiple sclerosis, autoimmune hepatitis, atopic...

 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

Immunosuppressive drug

Immunosuppressive drugs or immunosuppressive agents are drugs that inhibit or prevent activity of the immune system. They are used in immunosuppressive therapy to:...

 like cyclosporin, tacrolimus

Tacrolimus

Tacrolimus is an immunosuppressive drug that is mainly used after allogeneic organ transplant to reduce the activity of the patient's immune system and so lower the risk of organ rejection...

, methotrexate

Methotrexate

Methotrexate , abbreviated MTX and formerly known as amethopterin, is an antimetabolite and antifolate drug. It is used in treatment of cancer, autoimmune diseases, ectopic pregnancy, and for the induction of medical abortions. It acts by inhibiting the metabolism of folic acid. Methotrexate...

etc. Liver transplantation may be required if patients do not respond to drug therapy or when patients present with fulminant liver failure.