Role of the liver in clearance and excretion of circulating carcinoembryonic antigen (CEA).
CEA is a glycoprotein with a molecular weight of 200,000 containing 55%-65% carbohydrate. The removal of only two sialic acid residues result in rapid uptake from the circulation by the liver and catabolism in the lysosomes. There is a receptor on the plasma membrane of the hepatocyte (hepatic binding protein) which recognizes galactosyl residues. About 70% of 125I-labeled intact CEA is cleared by the liver in 1 hr. The exposure of terminal galactose residues by removing sialic acids determines the rate of clearance. CEA is probably initially taken up by Kupffer cells and transferred to hepatocytes. About 10% of CEA added to an isolated perfused liver appears in bile. Biliary duct obstruction and cholestasis may elevate plasma CEA levels due to detergent effects on the liver cell receptors.
D000818:Animals; D000951:Antigens, Neoplasm; D001646:Bile / Q000378:metabolism; D002241:Carbohydrates / Q000097:blood; D002272:Carcinoembryonic Antigen / Q000097:blood* / Q000378:metabolism; D015815:Cell Adhesion Molecules; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002779:Cholestasis / Q000378:metabolism; D006023:Glycoproteins / Q000097:blood; D006801:Humans; D007728:Kupffer Cells / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008107:Liver Diseases / Q000378:metabolism; D008657:Metabolic Clearance Rate; D012794:Sialic Acids / Q000502:physiology
D000951:Antigens, Neoplasm; D002241:Carbohydrates; D002272:Carcinoembryonic Antigen; D015815:Cell Adhesion Molecules; D006023:Glycoproteins; D012794:Sialic Acids