Autoantibodies in the diagnostics, prognostics and follow-up of primary biliary cholangitis

Primary biliary cholangitis (PBC), is a chronic autoimmune liver disease, characterized by cholangiopathy, cholestasis and in the long-term fibrosis, biliary cirrhosis and ultimately end-stage liver disease unless liver transplantation is applied. The diagnostics of PBC is based on biochemical tests, autoantibody measurements and liver histopathology. Abdominal ultrasound, later magnetic resonance cholangiopancreatography (MRCP) or endoscopic ultrasound can be effective methods for imaging the intra- and extrahepatic bile ducts. Concerning autoantibodies, anti-mitochondrial (AMA) and PBC-specific antinuclear antibodies (ANA) are the front-line tests that can be identified by indirect immunofluorescence tests or solid-phase immunoassays. AMA and especially the AMA-M2 variant have a high sensitivity and specificity for PBC, while anti-gp210 and anti-sp100 (PBC-specific ANAs) have a lower sensitivity but very high specificity for the disease. Anti-centromere antibodies (ACA) can help in the diagnostics of PBC and some overlap syndromes. Novel emerging markers - anti-hexokinase 1 and anti-Kelch-like 12 protein (anti-KLHL12) - can help the identification of rare AMA- and ANA-negative PBC cases. There is cumulating evidence that beside diagnostics certain autoantibodies can provide information about the prognostics of PBC, can predict therapy response, furthermore, can act as activity marker in follow-up of the patients during therapy. We summarize here the most important data about the accepted and potential clinical applications of traditional and emerging new autoantibodies in PBC.