Effect of proton pump inhibitor, omeprazole, on expression of rat parietal cell specific carbohydrate antigen, type 2 chain N-acetyllactosamine.

The effect of a proton pump inhibitor, omeprazole, on the rat gastric mucosal expression of carbohydrate antigens was studied. Type 2 chain N-acetyllactosamine was detected specifically on the apicocanalicular cell membranes of parietal cells. Pretreatment of rats with omeprazole profoundly suppressed the antigen expression, which followed the inhibition of gastric acid secretion. When omeprazole was discontinued, the antigen was reexpressed, which preceded the restoration of acid secretion. The antigen-negative tissues became antigen-positive when they were desialylated. Gastric membrane vesicles from the normal and omeprazole-treated rats were antigen-positive and -negative, respectively. SDS-PAGE revealed that a glycoprotein with an apparent molecular weight of 64-78 kDa carried type 2 chain N-acetyllactosamine. In the omeprazole-treated rats, the same molecular weight glycoprotein was positively immunostained only after desialylation. We concluded that: (1) the expression of type 2 chain N-acetyllactosamine was closely correlated with gastric acid secretion, and (2) the inhibition of acid secretion was accompanied by the sialylation of the parietal cell membrane glycoprotein.

The hepatocellular expression of a carbohydrate antigen 'sialyl Lewis X' in chronic hepatitis. A novel histological marker for active hepatic necroinflammation.

The hepatocellular expression of the carbohydrate antigen sialyl monomeric Lewis X (SMLex) and sialyl oligomeric Lewis X(SOLex) in chronic hepatitis was examined using specific monoclonal antibodies. Both of these sialyl Lewis X (SLex) antigens were membranously expressed in chronic hepatitis in spite of their absence in normal liver. Although SMLex was detected in mild hepatic inflammation, the expression of SOLex was associated only with moderate to severe necroinflammation. Hepatocellular expression of these antigens increased significantly as histological diagnosis advanced. Chronological observation also showed the change of SLex expression according to the histological change. The present observations suggest that hepatocellular SLex is a novel histological marker with a close correlation to the severity of necroinflammation in chronic hepatitis.

Hepatocellular expression of a novel glycoprotein with sialylated difucosyl Lex activity in the active inflammatory lesions of chronic liver disease.

Hepatic expression of sialylated difucosyl Lex antigen (SDLex, NeuAc alpha 2-3Gal beta 1-4(Fuc alpha 1-3)GlcNAc beta 1-3Gal beta 1-4(Fuc alpha 1-3)GlcNAc beta 1-) was studied with monoclonal antibody FH6, which defines this structure. Hepatocytes in the severe form of chronic active hepatitis and liver cirrhosis strongly expressed SDLex. The antigen was only weakly and focally detected in chronic persistent hepatitis. The mild form of chronic active hepatitis showed intermediate expression. SDLex expressed along the liver cell membranes displayed a honeycomb pattern when extensively expressed in the severe form of chronic active hepatitis or in liver cirrhosis. Cytoplasmic expression was faint and focal. Preferential tissue distribution was at the periphery of the hepatic lobules where the distruction of the limiting plate was present. The antigen was also expressed in sinusoidal lining cells and polymorphonuclear cells but not in the biliary epithelia. Hepatocytes expressing SDLex did not express related carbohydrate antigens, ie, Type 2 chain N-acetyllactosamine, Lex, and sialylated Lea. On subcellular fractionation, the microsome fraction contained the majority of the antigen activity. SDS-PAGE and Western blot analysis revealed one major SDLex-active glycoprotein with an apparent molecular weight of 110 kilodaltons. This glycoprotein was different from SDLex-active glycoproteins found in the sera of cancer patients. No ganglioside showed FH6 reactivity. These results indicate that liver cells in active inflammatory lesion expressed a novel glycoprotein carrying SDLex antigen in honeycomblike membrane-associated pattern.