Primary biliary cholangitis

Clinical information

Primary biliary cholangitis (PBC) is an immune-mediated chronic inflammatory cholestatic liver disease of unknown aetiology. The disease is characterised by female predominance (>90%) with most cases observed between the ages of 40 and 60. PBC incidence in different parts of the world is estimated to be 4 to 31 cases/million per year. PBC is marked by lymphocellular infiltration around the small intra-hepatic biliary ducts (bile canaliculi) and the build-up of bile (cholestasis). The disease often begins with unspecific, very varying general symptoms, such as itching (pruritus), fatigue and pain in the upper right region of the abdomen. An obstructive jaundice develops after a varying period of time. The increase in serum lipids is an important indicator for PBC. Histologically, changes occur in the liver corresponding to a chronic, non-suppurative destructive cholangitis: granulating pericholangitis, i.e. slowly progressing destruction of the small and medium-sized biliary ducts with subsequent fibrosis, the final stage of which is complete cirrhosis. In addition to the liver, often other organs with exocrine functions are also affected, above all the lachrymal and salivary glands and the pancreas.

Diagnostics

The diagnosis of PBC includes liver function tests (determination of alkaline phosphatase, aspartate transaminase and alanine transaminase), the determination of serum lipids, screening for anti-mitochondrial antibodies (AMA) and anti-nuclear antibodies (ANA) and the differentiation from other chronic inflammatory diseases of the liver, such as chronic viral hepatitis, autoimmune hepatitis or primary sclerosing cholangitis.

The detection of AMA is of great importance in the diagnosis of PBC. Antibodies against the M2 antigen are the most sensitive and specific diagnostic marker. These antibodies can be found in 94% of PBC patients. High-titer anti-M2 antibody seropositivity is an important tool in the diagnosis of PBC and a very powerful predictor of future development of PBC in patients without significant liver function disorders or symptoms suggestive of cholestatic diseases. Besides AMA, ANA may also be found in about one third of patients with PBC by indirect immunofluorescence. Promyelocytic leukaemia (PML) proteins and Sp100, which generate a nuclear dot pattern in IIFT, and two components of the nuclear pore complex (gp210 and p62) that have been specifically associated with a perinuclear pattern have been identified as specific ANA target antigens in PBC.