title: Automated enzymatic mitochondrial antibody assay for the diagnosis of primary biliary cirrhosis: applications of a routine diagnostic tool for the detection of antimitochondrial antibodies.
abstract: OBJECTIVE
  An automated enzymatic mitochondrial antibody assay (EMA) kit for the diagnosis of primary biliary cirrhosis (PBC) has become commercially available recently. The aim of this study was to assess the clinical utility of the enzyme inhibition assay using this EMA kit for the diagnosis of PBC.
  
  
  METHODS
  We tested the immunoreactivity of sera from 54 histologically confirmed Japanese PBC patients to the 2-oxo-acid dehydrogenase complex (2-OADC) enzymes by enzyme inhibition assay using commercially available TRACE (EMA) assay kit, and compared the results with those of indirect immunofluorescence, commercial enzyme-linked immunosorbent assay (ELISA) using MESACUP Mitochondria M2 kit, and immunoblotting on bovine heart mitochondria.
  
  
  RESULTS
  Of the 54 sera, 43 (80%) were positive for antimitochondrial antibodies (AMA) by immunofluorescence, 39 (72%) for enzymatic inhibitory antibody to pyruvate dehydrogenase complex (PDC) by EMA, 33 (61%) for immunoglobulin G (IgG) class anti-PDC antibody by ELISA, and 53 (98%) for IgG, IgM, or IgA class antibodies against at least one of the 2-OADC enzymes by immunoblotting. Of these, 43 (80%) were positive for IgG, IgM, or IgA class antibodies against the E2 subunit of PDC (PDC-E2) by immunoblotting. Thirty-six of the 54 sera (67%) showed identical results in all of the four assays, and 40 (74%) were all negative or positive by EMA, ELISA, and immunoblotting in PDC-relevant reactivity. There was a significant correlation between the number of detected immunoglobulin classes of anti-PDC-E2 by immunoblotting and anti-PDC by EMA (P < 0.0001), and a significant inverse correlation between IgG class anti-PDC by ELISA and units of PDC activity by EMA (r = -0.87, P < 0.0001).
  
  
  CONCLUSIONS
  Although EMA had lower sensitivity compared with immunofluorescence and immunoblotting, this assay should be included among the routine diagnostic tools for the detection of AMA specific to PBC in clinical laboratories because of its high specificity, objective read-out, and rapid turnaround time.
authors: Second Department of Internal Medicine, Nagasaki University School of Medicine, Graduate School of Pharmaceutical Science, Nagasaki University, Nagasaki, Japan.
authors: Hiroaki
authors: H
authors: Hazama
authors: Katsuhisa
authors: K
authors: Omagari
authors: Jun-Ichi
authors: J
authors: Masuda
authors: Kazuo
authors: K
authors: Ohba
authors: Hideki
authors: H
authors: Kinoshita
authors: Isao
authors: I
authors: Matsuo
authors: Hajime
authors: H
authors: Isomoto
authors: Yohei
authors: Y
authors: Mizuta
authors: Kunihiko
authors: K
authors: Murase
authors: Ikuo
authors: I
authors: Murata
authors: Shigeru
authors: S
authors: Kohno
mesh_terms: D000328:Adult; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D015151:Immunoblotting; D008105:Liver Cirrhosis, Biliary / Q000175:diagnosis*; D008297:Male; D008928:Mitochondria / Q000276:immunology; D011768:Pyruvate Dehydrogenase Complex / Q000276:immunology
chemical_list: D011768:Pyruvate Dehydrogenase Complex