High prevalence of anti-mitochondrial antibodies among patients with some well-defined connective tissue diseases.

A sensitive enzyme linked immunosorbent assay for determination of low levels of anti-mitochondrial antibodies (AMA) has been developed. With this method, sera from patients with primary biliary cirrhosis (PBC) and patients with different connective tissue diseases were investigated. Ninety percent of PBC sera were found to harbour high levels of AMA and a high proportion of patients with systemic lupus erythematosus (SLE), but also other patients with connective tissue diseases were found to have low affinity or low concentrations of AMA in their sera. AMA positive sera were further investigated with sodium dodecyl sulphate polyacrylamide gel electrophoresis and immunoblotting technique. PBC showed reactivity to 70, 50 and 45 kD mitochondrial polypeptides. SLE sera showed reactivity to 70 and 45 kD polypeptides and furthermore to a 65 kD polypeptide. Many of the AMA positive sera from patients with connective tissue diseases reacted to a 65 kD polypeptide.