title: Enzyme inhibitory autoantibodies to pyruvate dehydrogenase complex in primary biliary cirrhosis: applications of a semiautomated assay.
abstract: Sera from patients with primary biliary cirrhosis inhibit the activity of the mitochondrial pyruvate dehydrogenase complex. We utilized this effect to develop a simple, miniaturized, semiautomated spectrophotometric assay as a diagnostic aid. The sera studied were from 71 patients with primary biliary cirrhosis and 62 other subjects. The assays included enzyme inhibition, immunofluorescence on HEp-2 cells, enzyme-linked immunosorbent assay using recombinant pyruvate dehydrogenase complex-E2 and immunoblotting on bovine heart mitochondria. With the 71 primary biliary cirrhosis sera, on which M2 antibody was detected by immunofluorescence in 64 (90%), antibodies against pyruvate dehydrogenase complex were detected in 53 (83%) by means of enzyme inhibition, in 57 (89%) by means of enzyme-linked immunosorbent assay and in 60 (94%) by means of immunoblotting. Of the 64 sera positive by immunofluorescence, 60 reacted with pyruvate dehydrogenase complex-E2 on immunoblotting, and the miniaturized enzyme inhibition assay was positive in 53 of these. The enzyme inhibition assay and enzyme-linked immunosorbent assay were calibrated to give a specificity of 100%. At this level, the sensitivities for detection of pyruvate dehydrogenase complex antibody were 83% and 87%, respectively. We found no significant changes in levels of reactivity with the enzyme inhibition assay or enzyme-linked immunosorbent assay according to disease stage. Treatment with cyclosporine was accompanied by a significant decrease in levels of antibody to pyruvate dehydrogenase complex-E2 that matched improved indexes of biochemical liver function.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Center for Molecular Biology and Medicine, Monash University, Clayton, Victoria, Australia.
authors.forename: K L
authors.initials: KL
authors.lastname: Teoh
authors.forename: M J
authors.initials: MJ
authors.lastname: Rowley
authors.forename: H
authors.initials: H
authors.lastname: Zafirakis
authors.forename: E R
authors.initials: ER
authors.lastname: Dickson
authors.forename: R H
authors.initials: RH
authors.lastname: Wiesner
authors.forename: M E
authors.initials: ME
authors.lastname: Gershwin
authors.forename: I R
authors.initials: IR
authors.lastname: MacKay
mesh_terms: D001323:Autoantibodies / Q000276:immunology*; D016572:Cyclosporine / Q000627:therapeutic use; D004797:Enzyme-Linked Immunosorbent Assay; D005069:Evaluation Studies as Topic; D005455:Fluorescent Antibody Technique; D006801:Humans; D015151:Immunoblotting; D008105:Liver Cirrhosis, Biliary / Q000201:enzymology* / Q000276:immunology* / Q000473:pathology; D011768:Pyruvate Dehydrogenase Complex / Q000037:antagonists & inhibitors / Q000276:immunology*; D013053:Spectrophotometry / Q000379:methods
chemical_list: D001323:Autoantibodies; D011768:Pyruvate Dehydrogenase Complex; D016572:Cyclosporine