Anti-mitochondrial antibody immunofluorescent titres correlate with the number and intensity of immunoblot-detected mitochondrial bands in patients with primary biliary cirrhosis

BackgroundPrimary biliary cirrhosis (PBC)-specific anti-mitochondrial antibodies (AMA), routinely detected by indirect immunofluoresnce, immunofix various mitochondrial antigens by immunoblot (IB). We have investigated whether there is a relationship between IFL-determined AMA titres and the number, intensity or pattern of IB-bands.MethodsBy computer-assisted imaging technology, an IB analysis using human liver mitochondrial preparation was performed in 100 AMA positive PBC samples, subdivided in 5 groups each consisting of 20 cases with very high, high, intermediate, low or borderline IFL titres and in 19 AMA-negative cases.ResultsReactivity to at least 1 mitochondrial band (range 1–12) was present in 114 (96%) cases. Reactivity to the major pyruvate dehydrogenase E2-subunit 74-kDa autoantigen positively correlated with AMA IFL titres but was absent in 25% IFL-positive cases. The intensity and number of IB-bands differed significantly among groups (p < 0.001). IFL AMA titres positively correlated with the total number (r = 0.8, p < 0.001) and the intensity of the IB-bands (r = 0.75, p < 0.001).ConclusionsOur study indicates that IFL-determined AMA relate to the number and intensity of immunofixed bands. Reactivity to PDC-E2 does not correlate with IFL titres in a considerable proportion of patients suggesting that detection methods of AMA need to be based in the entire spectrum of the disease-specific mitochondrial antigens.