Identification of biliary antigens in circulating immune complexes in primary biliary cirrhosis

The presence of biliary tract antigens in circulating immune complexes from patients with primary biliary cirrhosis (PBC) was investigated. Concentrations of immune complexes in PBC sera, measured by the Raji cell immunoassay, ranged from 58 to greater than 1,000 microgram/ml, but did not correlate with disease activity. Immunofluorescent staining of complexes bound to Raji cells was carried out with guinea-pig antiserum raised against biliary tract antigens. Positive staining reactions were observed with complexes obtained from PBC patients, but not with those obtained from patients with systemic lupus erythematosus or rheumatoid arthritis, indicating that in PBC antigenic components associated with the biliary tract are contained within the complexes.