Specificity and sensitivity of gp210 autoantibodies detected using an enzyme-linked immunosorbent assay and a synthetic polypeptide in the diagnosis of primary biliary cirrhosis

Between 10% and 42% of patients with primary biliary cirrhosis (PBC) have been reported to have autoantibodies directed against a restricted epitope of gp210, a glycoprotein of the nuclear pore membrane. The prevalence and specificity of these antibodies was studied in a French series of 285 patients with PBC and 497 control individuals affected with other liver or autoimmune diseases. Sera were analyzed by an enzyme-linked immunosorbent assay (ELISA) that used a synthetic polypeptide containing the predominant autoepitope of gp210, in parallel to immunoblotting of gp210 protein and immunofluorescence microscopy. Autoantibodies to the gp210 epitope detected by ELISA were 25.5% sensitive and 99.5% specific for the diagnosis of PBC. These results were in agreement with a 99.4% specificity with immunoblotting analysis and a 96.6% specificity with immunofluorescence. In a subset of PBC patients without detectable antimitochondrial autoantibodies (AMA), gp210 autoantibodies were found in 7 of 15 patients (47%). Therefore, gp210 autoantibodies are highly specific for PBC and may be of particular utility in assessing patients without AMA or with other atypical presentations.