Human biliary mucin : purification, characterization, and its serum levels in liver diseases

Human biliary mucin was isolated using Sepharose 6B gel chromatography and equilibrium density gradient centrifugation in caesium chloride. The carbohydrate and amino acid composition of mucin from patients with cholesterol gallstones was essentially the same as that from patients with pigmented gallstones. The molar ratio of galactosamine : glucosamine : galactose : fucose : sialic acid was 1:3:2~4:3~5:0.5. Serine, threonine, and glycine were major amino acids. Anti-mucin antibody was raised in a rabbit, and was found to be specific for human biliary mucin. Serum levels of antibody-reactive proteins were significantly elevated in patients with acute and chronic liver diseases, and patients with gallstones. They were significantly higher in chronic parenchymal liver disease patients than in acute hepatitis patients, and in liver cirrhosis and hepatocellular carcinoma patients than in chronic hepatitis patients. The levels in gallstone patients were comparable to those in chronic hepatitis patients. The present results suggest that 1) the carbohydrate composition of mucin dose not differ between cholesterol gallstones and pigmented gallstones, 2) serum mucin, which reacts with the antibody against biliary mucin, is increased in liver disease patients, and this mucin might originate from the biliary tract, and 3) among liver disease patients, those with liver cirrhosis and hepatocellular carcinoma have the highest serum mucin.