Comprehensive Panel for autoimmune liver diseases includes determination of the following 12 autoantibodies: M2/nPDC, M2/OGDC-E2, M2/BCOADC-E2, M2/PDC-E2, gp210, sp100, LKM-1, LC-1, SLA/LP, F-actin, antinuclear antibodies (ANA) and atypic anti-neutrophil cytoplasmic antibodies (aANCA).
Autoimmune liver diseases are a group of conditions in which the body's immune system mistakenly attacks the liver cells, leading to inflammation and damage. There are several types of autoimmune liver diseases, and they can affect people of all ages. Some common autoimmune liver diseases include:
- Autoimmune Hepatitis (AIH): Autoimmune hepatitis is a chronic inflammatory liver disease characterized by immune system attacks on liver cells. It has two main types: Type 1 and Type 2.
- Primary Biliary Cholangitis (PBC): Formerly known as primary biliary cirrhosis, PBC is characterized by the progressive destruction of the small bile ducts within the liver. Over time, this damage can lead to cirrhosis.
- Primary Sclerosing Cholangitis (PSC): PSC is characterized by inflammation and scarring of the bile ducts, leading to the narrowing and obstruction of these ducts. It is often associated with inflammatory bowel diseases such as ulcerative colitis.
- Overlap Syndromes: Some individuals may exhibit features of more than one autoimmune liver disease, leading to the classification of overlap syndromes.
Symptoms: Symptoms of autoimmune liver diseases can include fatigue, jaundice, abdominal pain, itching, and in advanced cases, symptoms of liver failure.
Treatment: Treatment for autoimmune liver diseases often involves immunosuppressive medications to dampen the immune system's overactivity and reduce inflammation in the liver. Corticosteroids and other immunosuppressants may be prescribed.
Monitoring: Regular monitoring of liver function, autoimmune markers, and other relevant parameters is crucial to assess the disease's progression and the effectiveness of treatment.
Complications: If autoimmune liver diseases are not properly managed, they can lead to complications such as cirrhosis, liver failure, and an increased risk of liver cancer.
Treatment plans may need to be adjusted over time, and regular follow-up is essential to monitor the liver's health and address any emerging issues promptly. Early diagnosis and appropriate management can significantly improve outcomes for individuals with autoimmune liver diseases.
Diagnosis: Diagnosis involves a combination of clinical evaluation, blood tests to detect specific antibodies and assess liver function, imaging studies, and, in some cases, a liver biopsy to evaluate the extent of liver damage.
The M2 antibodies belong to the Anti-Mitochondrial Antibodies (AMA) group and are strongly associated with PBC. At least 9 distinct AMA have been identified, classified M1-M9 according to their antigen specificity and disease association. Of these, only the M2 subtype approaches absolute specificity for PBC. Indeed, about 95% of PBC patients have M2 autoantibodies and, conversely, about 90% of asymptomatic individuals who are found to be M2-positive on routine screening can be shown to have underlying PBC on further investigation.
The target antigens of M2 antibodies have been identified as components of the 2-Oxo-Acid Dehydrogenase Complex, the immune-dominant epitopes being located on the E2 subunits of Pyruvate Dehydrogenase Complex (M2/PDC-E2), Branched-Chain Oxo-Acid Dehydrogenase Complex (M2/ BCOADC-E2) and Oxo-Glutarate Dehydrogenase Complex (M2/OGDC-E2). In most patients, anti-M2 antibodies are directed against various combinations of different epitopes/antigens. Particular cases are however regularly documented where they recognize a single epitope, on a single subunit. This induces discordances between tests, depending on the antigen used. Indeed, a high correlation with IFA results is obtained by using native PDC (M2/nPDC) alone.
The main diagnostic marker for PBC is Anti-Mitochondrial antibodies (AMA). However, 5 to 10 % of PBC patients do not present AMA. Some of these patients present PBC-specific antinuclear antibodies such as antibodies to nuclear dots (sp100), antibodies to the nuclear membrane (gp210), and antibodies to centromeres.
Anti-gp210 antibodies are highly specific to Primary Biliary Cirrhosis (PBC). Anti-gp210 antibodies are also reported to be associated with extra-hepatic manifestations such as arthritis.
sp100 is a 100 kD protein of the nuclear body and anti-sp100 antibodies are highly specific to Primary Biliary Cirrhosis (PBC). Anti-sp100 has also been described in some rare cases of rheumatoid arthritis, Systemic Lupus Erythematosus (SLE), Systemic Sclerosis, and Sjögren’s syndrome.
