Anti-mitochondrial autoantibodies—milestone or byway to primary biliary cholangitis?

Anti-mitochondrial autoantibodies (AMA) are a signature autoantibody of primary biliary cholangitis (PBC), formally known as primary biliary cirrhosis (1), and are detected in sera of 95% of patients with PBC, while scarcely found in patients with other disorders including autoimmune diseases (2,3). Based on this high specificity and sensitivity of AMA for diagnosis of PBC, clinical practice guidelines from the US, Europe and Japan strongly agree with the diagnosis criteria of PBC (4-6). Namely, the diagnosis of PBC can be made if a patient meets at least two of three items; chronic elevation of cholestatic enzymes, presence of AMA, and histological findings consistent with PBC. Even in patients in whom AMA are not found in sera with routine method such as indirect immunofluorescence using rat liver, kidney and stomach tissue sections, AMA can be detected with other methods with high sensitivity such as ELISA or immunoblotting using recombinant mitochondrial proteins as antigens (7,8). Thus, detection of AMA is a robust hallmark of PBC, and therefore it is not surprising that researchers are tempted to consider that AMA are not a simple biomarker of PBC but are closely related to etiology of the disease.