Autoimmune Hepatitis (AIH): Overview, Types and Biomarker Tests 

What is Autoimmune Hepatitis?

Your immune system makes a large number of antibodies and lymphocytes, which help fight off infections in healthy adults. However, sometimes, your body's immune system turns against its own liver cells, causing liver inflammation. This inflammation is called autoimmune hepatitis (AIH). While the exact cause of autoimmune hepatitis is hard to determine, genetic and environmental factors are known to trigger the disease.

When detected early, autoimmune hepatitis can be controlled with drugs that suppress the immune system. However, if left untreated, it can lead to scarring of the liver (cirrhosis), gastrointestinal bleeding, confusion associated with a poorly functioning liver, and even liver failure. In advanced cases, a liver transplant may be a viable option. Symptoms of the disease vary from person to person. However, common symptoms include jaundice, severe fatigue, joint pain or swelling, abdominal pain or ascites (development of fluid in the abdomen) and spider-like blood vessels in the skin, to name a few.

Types of AIH

Two primary types of Autoimmune Hepatitis have been identified clinically. These include:

Type 1 Autoimmune Hepatitis: This is the more common type of disease that can occur at any age, although it is commonly diagnosed in adulthood and predominantly affects young women. It is known as the classic variant. It is the milder form of the disease and is fairly responsive to treatment if begun early. About half the people with type 1 AIH also suffer from other autoimmune disorders such as rheumatoid arthritis, celiac disease, or ulcerative colitis.

Type 2 Autoimmune Hepatitis: This form of the disease is less common and more severe. It is more commonly found in children and young people — primarily in girls between the ages of 2 and 14. This may be more difficult to control.

Biomarkers in Autoimmune Hepatitis

A series of specialized blood tests can be used to determine the proper functioning of the liver. These include:

1. Antinuclear Antibody (ANA) Test

This blood test looks for the presence of antinuclear antibodies in the blood. Proteins made by your immune system to fight foreign substances are known as antibodies, but antinuclear antibodies attack healthy cells. ANA is positive in about 50-75% of patients who have autoimmune hepatitis. Antinuclear Antibody Test serves as a key diagnostic finding in autoimmune hepatitis (AIH) type 1.

2. Smooth Muscle Antibody (SMA) Test

This test looks for the presence of smooth muscle antibodies — a type of autoantibody — in the blood. Smooth muscle tissues in the liver and other parts of the body are attacked by SMAs. In addition to diagnosing the presence of AIH, this test is also used to determine if the disorder is type 1 or type 2.

3. Liver Kidney Microsome Type 1 (anti-LKM-1) Test

Liver kidney microsome type 1 is a type of autoantibody that recognises and targets its own enzyme called cytochrome P450 2D6 (CYP2D6), which is a protein found primarily in the liver cells. Liver kidney microsome type 1 (anti-LKM-1) test detects and measures the amount of anti-LKM-1 in the blood. The presence of this indicates autoimmune hepatitis type 2.

4. Antimitochondrial Antibody (AMA) M2 Test

Antimitochondrial antibodies (AMA) are formed against mitochondria — the energy source of your cells. The presence of the M2 antigens of AMA indicates AIH.

5. M2 3E Test

M2 3E is a fusion protein that consists of different subunits of the M2 enzyme complex of mitochondria. Its presence is used to aid in the diagnosis of primary biliary cirrhosis and AIH.

6. Sp100 Test

Sp100 antibodies are typically detected in patients with liver ailments such as primary biliary cholangitis and AIH. The test is recommended when patients test negative for AMA.

7. PML Test

Promyelocytic leukaemia (PML) protein is a type of antinuclear antibody (ANA) that is associated with the presence of autoimmune hepatitis.

8. GP-210 Test

Gp210 is an integral glycoprotein of the nuclear pores. Patients suffering from AIH frequently produce autoantibodies against gp-210. Thus, this test is used in conjunction with others to determine the presence of liver ailments such as AIH and even primary biliary cirrhosis (PBC). Research suggests that the presence of antibodies is a strong marker for the disease and is also associated with an aggressive disease course.

9. LC-1 Antibody Test

The Liver Cytosolic Antigen Type 1 (LC-1) Antibody test is used to evaluate for autoimmune hepatitis of unknown aetiology in combination with Liver-Kidney Microsome - 1. More than 50% of cases with type 2 AIH show the presence of antibodies against LC-1.  Although it is most commonly seen with LKM-1 antibodies, there have been instances of its presence as isolated occurrences in about 10% of cases. A high level of anti-LC-1 is associated with a more serious disease course.

10. Anti SLA/LP Test

Antibodies against soluble liver antigen/liver pancreas (anti-SLA/LP) are highly specific for autoimmune hepatitis (AIH) type 1. It is a strong marker for the disease and has been linked with a more aggressive strain of the disease, frequent relapses after treatment withdrawal and challenging clinical outcomes. Anti-SLA may occur without the presence of ANA and or SMA.

11. Anti Ro-52 Test

The Ro-52 antigen is a complex ribonucleoprotein, and antibodies against Ro-52 are associated with several different autoimmune conditions, including autoimmune hepatitis.

The Bottom Line

Autoimmune Hepatitis is a challenging disease, but one which can be controlled and managed if diagnosed early and you undergo treatment for the same. The above-mentioned biomarkers are indicators of the disease and serve as determinants of the disease’s presence as well as sub-type. Metropolis conducts a complete spectrum of liver profile tests to diagnose autoimmune hepatitis and provide definitive results which can help your healthcare provider determine your future course of treatment. Do understand that a further series of tests along with a liver biopsy may be required for confirmation of the disease as well as its progressive stage.

Please do not hesitate to connect with us or with your healthcare provider for a greater understanding of the above-mentioned biomarkers.