P.A. Berg

ATPASE-ASSOCIATED ANTIGEN (M2): MARKER ANTIGEN FOR SEROLOGICAL DIAGNOSIS OF PRIMARY BILIARY CIRRHOSIS

Serum samples from 94 patients with primary biliary cirrhosis (PBC) and 17 patients with chronic cholestatic hepatitis (CCH) were tested in the fluorometric immunoassay (FIAX) against the nonorgan-specific ATPase-associated antigen (M2) and against submitochondrial from beef heart and rat liver, to evaluate the specificity and sensitivity of the M2 antigen for the diagnosis of PBC. As controls serum samples from 42 patients with other antimitochondrial antibody (AMA) specificity (against M1, M3, M5, and M6) as well as samples from 417 patients with various other hepatic and non-hepatic disorders were used. Serum samples from 91 of the 94 PBC patients (97%) and all 17 with CCH reacted with the M2 antigen. However, when SMP from rat liver and beef heart were tested in parallel in the FIAX, AMA could be detected in all PBC serum samples. None of the 42 patients with different types of AMA had reactions with the M2 antigen but all had reactions with SMP from rat-liver or beef-heart mitochondria or both. Among the other 417 patients with hepatic and non-hepatic disorders only 4(1%), all with collagen diseases, had anti-M2 antibodies.

Use of ATPase-associated antigen (M2) for detection of antimitochondrial antibodies in primary biliary cirrhosis by fluorometric immunoassay

An indirect binding assay, the fluorometric immunoassay (FIAX), was established for the detection of anti-M2 antibodies which are specific markers for primary biliary cirrhosis (PBC). Submitochondrial particles (SMP) from beef heart and rat liver and the ATPase-associated antigen (M2) were used. The antigens were fixed to a cellulose acetate surface, SMP at a concentration of 2 mg/ml, ATPase at a concentration of 0.2 mg/ml. Sera were used at 1:60 and 1:120 and bound antimitochondrial antibodies (AMA) were demonstrated by fluorescent isothiocyanate labelled monospecific anti-human IgG, IgM and IgA antibodies. The fluorescent signals were proportional to the AMA titre in the serum samples and were measured in a fluorometer (FIAX 100). Of 94 patients with PBC, 92 had AMA against SMP from beef heart compared with 76 in the complement fixation test (CFT) and 84 in the immunofluorescence test (IFL). Ninety reacted with the ATPase-associated M2 antigen. Sera from patients known to have AMA of different specificities (anti-M1, anti-M3, anti-M5, anti-M6) reacted with SMP from beef heart and/or rat liver but not with M2.

Nuclear Antibodies in Autoimmune Liver Diseases Defined by Immunoprecipitation and Cell Culture Substrates

Publisher Summary This chapter reviews nuclear antibodies in autoimmune liver diseases defined by immuno-precipitation and cell culture substrates. Subtypes of antinuclear antibodies (ANA) have been demonstrated to be specific markers for the serological diagnosis of some forms of connective tissue diseases (CTD). They could be detected using soluble extracts from rabbit thymus and human spleen in the immuno-diffusion (ID) and cell cultures substrates in the indirect immunofluorescence test (IFL). There is evidence, that also sera from patients with autoimmune liver diseases contain antibodies against nuclear antigens when tested on cell cultures or against thymus extract in the counter immuno-electrophoresis (CIE). Sera from 166 patients with primary biliary cirrhosis (PBC), 86 patients with autoimmune chronic active hepatitis (CAH), 50 patients with other hepatic disorders (HBsAg positive CAH, alcoholic liver disease, primary sclerosing cholangitis), and 100 blood donors were examined in CIE and IFL on cell lines. Additionally, sera from 99 patients with non hepatic autoimmune diseases (SLE, scleroderma, polymyositis) were tested by CIE.