AMA-M2

AMA-M2

AMA M2 - 3E - antibodies to the main epitope of antimitochondrial antibodies of type 2. They are found together with AMA-M2 in patients with primary biliary cirrhosis, their detection increases the sensitivity of the examination. AMA is a heterogeneous group of autoantibodies against various proteins located on the inner and outer membranes of mitochondria. Antigen by structure is a lipoprotein, which participates in the transport functions of the membrane. It is possible to determine both total and individual antibody subtypes. At present, 4 subtypes of AMA are isolated. For primary biliary cirrhosis (PBC), antibodies to the mitochondrial antigen M-2 , which is the E2 subunit of the pyruvate dehydrogenase complex ( E2-PDH, are considered specific). Diagnostic sensitivity is 98%, specificity is 96%. PBC is a chronic liver disease that occurs with a nasal, destructive inflammation and obstruction of the intrahepatic bile ducts and the development of hepatic insufficiency. In a third of patients, other autoantibodies (ANA, SMA) are detected. AMA can be detected in patients with PBC for many years before the manifestation of the disease. The presence of AMA is considered as a sign of "preclinical" PBC (10-15% of patients). Up to 80% of cases of PBC are associated with other AIZ: more often with Sjogren's syndrome and hypothyroidism, which appears before PBC. Approximately 10-20% of patients with PBC develop secondary AIG (CC). The frequency of detection of AMA-2 in AIG is 17-34%. The detection of AMA in AIG-1 can identify a subpopulation of patients at risk of developing cholestasis syndrome. AMA is used to differentiate 2 homogeneous groups of patients with the variant CC-AIG + PBC: AMA-negative patients have a lower level of transferases, higher levels of alkaline phosphatase and GGTP, all have ANA or SMA, they are characterized by more severe bile duct damage, including destructive cholangitis , ductopenia, duct hyperplasia and fibrosis.