Carbohydrate moieties of glycoproteins in human hepatic and gall-bladder bile, gall-bladder mucosa and gall stones

Abstract

1. The soluble glycoproteins of human bile, gallbladder mucosa and gall stones have been extracted and hydrolysed, and the monosaccharides analysed by gas-liquid chromatography. 2. Human biliary glycoproteins contained 55-75% of carbohydrate, the major monosaccharide components being galactose, fucose and N-acetylglucosamine, accounting for 70-85% of all the monosaccharides. Mannose, glucose, N-acetylgalactosamine and N-acetylneuraminic acid (sialic acid) were also present. N-Acetylneuraminic acid was present in large amounts in the gall-bladder mucosa and bile of one ulcerated and markedly inflamed gall bladder. 3. The proportion of monosaccharides in soluble glycoproteins of mucosa and bile were not different in samples from subjects with or without gall stones. 4. Gall stones were analysed for cholesterol, calcium and bilirubin and classified as 'cholesterol stones' (7/10) and 'pigment stones' (3/10). Both cholesterol and pigment stones contain a variable amount of glycoprotein. The pattern of carbohydrate consituents was similar to that present in the gall-bladder mucosa and bile in the same subject. There was also no major difference between the pattern found in 'cholesterol' and 'pigment' stones. 5. Evidence and argument are presented suggesting that some glycoprotein is secreted by the gall bladder and incorporated into gall stones. This calls for further work upon the influence of these carbohydrate-rich macromolecules on cholesterol solubilization in mixed micelles.