Detection of anti-pyruvate dehydrogenase complex antibody in primary biliary cirrhosis by an enzyme-linked immunosorbent assay.

The methods to detect antimitochondrial antibodies (AMAs), which are characteristically positive in primary biliary cirrhosis (PBC), have some problems in technical difficulty, sensitivity and specificity. Based on the finding that one of the major antigens corresponding to AMAs was the E2 component of pyruvate dehydrogenase complex (PDH), a very simple enzyme-linked immunosorbent assay (ELISA) to detect anti-PDH antibody (anti-PDH) has been developed in this study. Among 68 patients with PBC, IgG class anti-PDH and IgM class anti-PDH were detected in 64 patients (94.1%) and in 55 patients (80.8%), respectively, while only three cases (4.4%) were both negative. Mean optical densities (O.D.) of sera from patients with PBC were 0.536 +/- 0.386 (mean +/- SD) in IgG class and 0.308 +/- 0.342 in IgM class. No positive cases were detected in the following patients by this ELISA: 20 patients with acute viral hepatitis, 24 with chronic persistent hepatitis, 32 with chronic active hepatitis, 19 with liver cirrhosis, 19 with hepatocellular carcinoma, 19 with acute intrahepatic cholestasis, 10 with autoimmune hepatitis, and six with systemic lupus erythematosus. Among nine AMAs negative cases with PBC by conventional indirect immunofluorescence (IF) assay, seven cases were found to be positive by this ELISA. The inter-assay coefficient of the variation of this method ranged from 4.9% to 5.8% and the intra-assay coefficient of variation from 3.8% to 5.1%. Therefore, this ELISA is useful for diagnosis of PBC.