[Effects of chronic ethanol intake on sugar chain structures of IgG in mice].

IgG is an N-glycosylated glycoprotein, and is secreted from B lymphocyte. Transferrin is also an N-glycosylated glycoprotein secreted from hepatic cell. We have investigated, by lectin-ELISA method, reactivities of sugar chain structures, which are Gal (beta 1, 4) GlcNAc, Fuc (alpha 1, 3 or 6) Gal, NeuAc (alpha 2, 6) Gal, galactose, poly mannoses and NeuAc (alpha 2, 3) Gal, in IgG or transferrin of ddY mice that were given ethanol solution for 3 weeks. In the investigation, we have found that the all reactivities of sugar chain structures in IgG and transferrin remarkably reduced. We have also found that Lewis-X (Gal (beta 1, 4) GlcNAc (3, 1 alpha Fuc)-), which is functional sugar chain structure in the IgG, was markedly reduced with dose-dependent manner. These findings indicate that ethanol decreases activities of glycotransferases in some cells which produce and secrete N-glycosylated glycoproteins. It has been reported that human erythrocyte has also N-glycosylated glycoproteins in the membrane, and its sialic acid and galactose are reduced after chronic ethanol intake. The past and present findings indicate that sugar chain structures of N-glycosylated glycoproteins in both serum and cell membranes are reduced after chronic ethanol intake. Though functions of sugar chain structures of N-glycosylated glycoproteins remain unclear, if functional structures like Lewis-X exist in N-glycosylated glycoproteins, the change of the sugar chain structures may have some relations to diseases occurring after chronic ethanol intake.