Journal of Immunological Methods, 60 (1983) 77-88 77 Elsevier Biomedical Press Detection of Mitochondrial Antibodies Directed against the Primary Biliary Cirrhosis (M2) Antigen by an Enzyme-Linked Immunosorbent Assay (ELISA) S. Nagai 1,,, M. Manns 1, K.-H. Meyer zum Biischenfelde 1.** and H.P. Dienes 2 ! L Medizinische Klinik und Poliklinik and 2 Institutfiir Pathologie, University ofMainz, Langenbeekstrasse 1, D-6500 Mainz, F.R.G. Received 16 September 1982, accepted 31 January 1983) An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of 1 subtype of mitochondrial antibodies (AMA) specific for chronic cholestatic inflammatory liver diseases. AMA were detected by ELISA in 16 of 16 patients with primary biliary cirrhosis (PBC) and in 2 of 31 patients with chronic active hepatitis. These 18 positive sera were positive for AMA by indirect immunofluorescence (IF) and by radioimmunoassay (RIA). No AMA were detected by ELISA in 2 patients with the pseudolupus erythematosus syndrome, who were positive for AMA by IF, 2 patients with secondary syphilis, positive for cardiolipin antibodies, l patient with systemic lupus erythematosus, positive for AMA by IF, 58 further patients with various hepatic and non-hepatic diseases and l0 healthy blood donors. The titers obtained by ELISA, ranging from 1:20 to 1:62,500, correlated well with those obtained by IF and RIA. The ELISA detected an AMA directed against one determinant of a mitochondrial antigen bearing the characteristics of the so-called PBC antigen (M2 antigen). The ELISA described is a sensitive and specific test for the detection of AMA directed against the PBC (M2) antigen and may be used not only as a standard method assaying this clinically important subtype of AMA but also as a tool for further purification and characterization of the PBC (M2) antigen. Key words: mitochondrial antibodies -- primary biliary cirrhosis -- hepatitis -- enzyme-linked immuno- sorbent assay (ELISA) Introduction Recently a radioimmunoassay (RIA) has been described which detects a subtype of mitochondrial antibodies (AMA) associated with chronic cholestatic inflamma- * Present address: The Third Department of Internal Medicine, Niigata University, Asahi-machi l, 951 Niigata, Japan. ** Address for correspondence: Prof. Dr. Dr. K.-H. Meyer zum BOschenfelde, I. Medizinische Klinik und Poliklinik der Johannes Gutenberg-Universitht, Langenbeckstr. 1, D-6500 Mainz, F.R.G. 0022-1759/83/0000-0000/$03.00 © 1983 Elsevier Science Publishers