What is a Liver cytosolic antigen type-1 (LC-1) Antibody?

The autoantibodies in autoimmune hepatitis (AIH) are extensively used for its diagnosis and classification. However, they are also useful for defining the prognosis and inferring clinical behavior.

For the Diagnosis and Classification of AIH

In accordance with the classical criteria for the diagnosis of AIH, the importance of autoantibody testing is diluted among 12 parameters. Only adult patients with autoantibody reactivity greater than 1/80 for the classical markers, such as anti-smooth muscle antibodies (ASMAs), anti-nuclear antibodies (ANAs), and anti-liver/kidney microsome type 1 (anti-LKM1) antibodies, score three points. When these markers are absent, other secondary antibodies, such as anti-soluble liver/pancreas antigen (anti-SLA/LP) and liver cytosol type 1 (anti-LC1), should be tested. It is possible to reach a definite diagnosis of AIH without any autoantibody reactivity, and this occurs in approximately 5–10% of all AIH cases.

Further, a simplified scoring system was proposed based on only four parameters: absence of viral hepatitis antibodies, increased IgG levels, typical histological features, and reactivity for liver autoantibodies (each with a maximum score of two points under standard specifications). As stated in the interpretation of these simplified criteria, it is impossible to have a definite diagnosis without any reactivity for autoantibodies, and we know this is not true.

The reactivity of autoantibodies in AIH is crucial for its classification. ASMAs and ANAs are markers of type 1 AIH (AIH-1), and anti-LKM1 and anti-LC1 antibodies are markers of type 2 AIH (AIH-2). Anti-SLA/LP antibodies were initially considered markers of the third type of AIH, but this subject is still under debate. The major autoantibodies, their corresponding target antigens, the techniques for their detection, and the main features of AIH.