Serum antimitochondrial autoantibodies (AMA) are the diagnostic hallmark of primary biliary cirrhosis (PBC), being detected in 90-95% of affected individuals. AMA autoantigens have been mapped within three structurally and functionally related multienzymic complexes located on the inner mitochondrial membrane, that is, the 2-oxoacid dehydrogenase complexes. More specifically, AMA most commonly are directed against lipoylated domains within the E2 subunit of the pyruvate dehydrogenase complex (PDC-E2). It is to note that AMA may appear years before the onset of PBC. Despite their high specificity for PBC, proof of a direct or indirect pathogenic role for AMA is still awaited. Moreover, AMA titers or specificity do not correlate or predict the clinical course of the disease. Novel methods for the detection of serum AMA are being developed that are increasing the sensitivity of the test. In the clinical environment, the routine method for serum AMA detection is indirect immunofluorescent that produces a typical pattern above, a titer higher than 1:40 is considered as positive. More recently, recombinant mitochondrial antigens have been made available. The use of these antigens, either by immunoblotting or enzyme-linked immunosorbent assay (ELISA), have significantly increased the sensitivity and specificity of the test. These tests, however, are currently available only for research purposes in selected laboratories.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)