Autoantibodies and Autoantigens in Autoimmune Hepatitis

Christian P. Strassburg, MD, Michael P. Manns, MD

Disclosures

Semin Liver Dis. 2002;22(4) 

In This Article

Autoimmune Hepatitis Type 1

ANA are a universal marker of immune-mediated diseases in humans. They are routinely determined as a diagnostic marker in a large number of immune-mediated diseases apart from autoimmune liver diseases,[34,39,40] which include rheumatological diseases. ANA have also been identified as a serological parameter in up to 52% of patients with primary biliary cirrhosis (PBC) ( Table 1 ). PBC is diagnosed based on the presence of antimitochondrial antibodies that are specific for this disease if they are directed against the E2 subunit of pyruvate dehydrogenase (anti-PDH-E2 autoantibodies) or other mitochondrial acyltransferases. The question is whether these antibodies can be employed to contribute to the diagnosis of PBC by identifying AMA-negative cases of PBC and excluding AIH type 1. Well-characterized are autoantibodies against a 210-kD glycoprotein of the nuclear membrane (GP 210)[41,42] that are highly PBC specific and occur in 10 to 47% of patients.[43] Nucleoporin p62 is targeted in 32% of PBC sera and also appears to be disease specific.[44] In about 20% of PBC patients, autoantibodies are detected against SP100, a nucleoprotein of 100 kD molecular weight.[45] One study has identified cyclin A as human autoantigen in hepatic and extrahepatic diseases.[33] Anti-cyclin A autoantibodies were detected in 7% of patients with PBC and more frequently in AIH type 1. Other ANA with low specificity for PBC, however, include the lamin B receptor[46] and promyelocytic leukemia-associated protein PML.[47] When ANA are detected in PBC, they frequently display unique immunofluorescence patterns such as nuclear dots (i.e., SP100) or a nuclear ringlike pattern (GP 210). Cases of these autoantibodies in patients with the clinical presentation of PBC and the absence of AMA are rare but may be the only seroimmunologic clue to establishing the diagnosis of PBC in a selected number of patients.

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