Development of a new enzyme-linked immunosorbent assay for the detection of anti-M2 in primary biliary cirrhosis.

We developed a new enzyme-linked immunosorbent assay (ELISA) for the detection of antimitochondrial antibody (AMA)-M2 in sera from patients with primary biliary cirrhosis (PBC), using 2-oxo-acid dehydrogenase complex (2-OADC) purified from porcine myocardium as the antigen source. The immunoreactivity was tested in a total of 354 sera, including 63 sera from patients with PBC by our ELISA. In the sera, indirect immunofluorescence for AMA, former ELISA for anti-pyruvate dehydrogenase complex (PDC) and immunoblot assay were performed, respectively. Of the 63 sera from patients with PBC, 51 sera (81.0%) were positive for anti-M2 in the new ELISA. Thirty-eight of the 63 sera (60.3%) were positive for anti-PDC in the former ELISA; the difference was significant between them (P=0.011). None of the 291 control sera from healthy volunteers showed reactivity against 2-OADC in the new ELISA. Moreover, in comparison with the results of immunoblot analysis, sensitivity and specificity in our ELISA to the sera from patients with PBC were 100 and 92.3%, respectively. Our results indicate that the new ELISA for anti-M2 using 2-OADC is simple, rapid and sensitive enough for the detection of AMA specific to PBC.