Autoimmune liver diseases are a group of rare chronic liver disorders caused by immune dysregulation, leading the immune system to attack hepatic structures. Primary biliary cholangitis (PBC)—formerly known as primary biliary cirrhosis—is a chronic autoimmune cholestatic condition affecting cholangiocytes, the epithelial cells of intrahepatic bile ducts. The disease progresses slowly and may lead to fibrosis, cirrhosis and, in later stages, liver transplantation. However, early diagnosis and appropriate treatment can significantly improve prognosis and help prevent progression to cirrhosis.
The diagnosis of PBC is based on biochemical abnormalities of the liver, ruling out other causes of chronic liver disease and the identification of specific autoantibodies, which represent key serological markers. Anti-mitochondrial antibodies (AMA) are detected in 90–95% of patients with PBC and are one of the main diagnostic criteria. In AMA-negative patients (5–10%), antinuclear antibodies (ANA) against antigens such as gp210, sp100, or centromere may be present and are valuable for the prognosis.
AMAs are a heterogeneous group of autoantibodies against components of the inner mitochondrial membrane. Based on their immunochemical reactivity, they are classified into subtypes M1–M9, but only anti-M2, M4, M8 and M9 are considered specific for PBC. Among these, AMA-M2 are by far the most diagnostically relevant, and are present at high titres in the majority of patients. The most common molecular targets are the E2 subunits of three mitochondrial enzyme complexes:
- PDC-E2 (pyruvate dehydrogenase)
- BCOADC-E2 (branched-chain 2-oxo acid dehydrogenase)
- OGDC-E2 (2-oxoglutarate dehydrogenase)
The gold standard for AMA screening is indirect immunofluorescence (IIFT) on rat kidney sections to detect the typical granular cytoplasmic pattern of AMAs. Solid-phase assays are more specific and are used to confirm AMA-M2 positivity and to provide a detailed antigenic characterisation.
Serum, EDTA plasma, heparin plasma, citrate plasma
Immunoblot
Fasting for at least 8-12 hours before sampling
Refer to the Health Service Charter to check storage conditions
+2/+8°C
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Test for the determination of human autoantibodies against NMDAR to support the diagnosis of paraneoplastic neurological syndromes with an intermediate-risk phenotype.
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