A dot-immunobinding assay was established for the detection of antimitochondrial antibodies. Nitrocellulose strips were coated with sonicated rat liver mitochondria and incubated in the presence of human sera. The resulting immune complexes were visualized with an enzyme-linked second antibody. Antimitochondrial antibodies were found in the sera of 9690 of patients with primary biliary cirrhosis, 17% of patients with autoimmune hepatitis and 4% of patients with progressive systemic sclerosis. Sera of patients with other liver diseases or with systemic lupus erythematosus, specimens positive for M1 and M 3 mitochondrial antibodies and samples from normal controls were all negative. Antinuclear and other cytoplasmic antibodies were not detected in this assay. The dot-immunobinding assay for antimitochondrial antibodies is rapid and sensitive, and obviates the need for expensive equipment.
Detection of antimitochondrial antibodies (AMA) has proved to be of value in the diagnosis of primary biliary cirrhosis (PBC; 1, 2 ) . AMA occur in sera of greater than 85% of PBC patients (1 1 and are only rarely encountered in other hepatic and nonhepatic diseases (3). They occur regardless of disease stage and therapy. Recent longitudinal studies suggest that AMA can occur years before symptoms of PBC and before the first biochemical changes appear (Mitchison, H. et al., Gastroenterology 1985; 86:1679, Abstract). Although AMA are probably not involved in the pathogenesis of PBC, they are a reliable marker for this disease.
Several methods are used for the detection of AMA (1, 2, 4-1 1). Immunofluorescence and enzyme-linked immunosorbent assays are the most widely used techniques. Both necessitate expensive equipment. In addition, immunofluorescence requires the recognition of typical staining patterns and is thus subject to observer errors.
Recently, the dot-immunobinding assay has gained acceptance as a sensitive serological tool for detection of antibodies and/or antigens [for review see Ref. (12)]. In tests for antibodies, antigens are dotted onto a solid support of nitrocellulose, incubated with a serum-containing antibody, and the immune complex then visualized with a labeled second antibody. The results are