Primary biliary cirrhosis (PBC) is a chronic inflammatory, cholestatic disease of the liver with an unknown cause. The clinical observation of a broad array of immune-mediated symptoms and phenomena suggests the disease to be of autoimmune aetiology, in the course of which small interlobular and septal bile ducts are progressively and irreversibly destroyed1. As in other autoimmune diseases, PBC affects women in over 90% of cases, and is associated with varying extrahepatic autoimmune syndromes occurring in up to 84%. These extrahepatic manifestations of immune-mediated disease include the dry gland syndrome (sicca syndrome with xerophthalmia and xerostomia) but also collagen diseases, autoimmune thyroid disease, glomerulonephritis and ulcerative colitis.The detection of circulating antimitochondrial antibodies (AMA) is the single most important serological test for the diagnosis of PBC, in particular when clinical serological and histological signs of cholestatic disease and evidence of bile duct destruction are not yet present2. Specific AMA are detectable in over 95% of patients with PBC, and are yet another indicator of autoimmune mechanisms underlying this condition3'4. In 20-50% of patients suffering from PBC, antinu-clear antibodies (ANA) are also detectable, and contribute to the definition of this disease2*5"7. Although none of these autoantibodies is tissue-, organ- or species-specific, AMA are highly disease-specific. Frequently, in particular in early disease, a clinical suspicion or the establishment of the diagnosis of PBC is based upon the detection of specific AMA as a single finding. Intense effort has been aimed at characterizing the molecular targets of PBC-associated AMA in order to improve and develop disease-specific serological test strategies8.
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