Effects of monocytic products, recombinant interleukin-1, and recombinant interleukin-6 on glycosylation of alpha 1-acid glycoprotein: studies with primary human hepatocyte cultures and rats

Abstract

Changes in the carbohydrate moieties of acute-phase glycoproteins (APGPs) often accompany the increase in their secretion by the liver during inflammation. In this study, we investigated whether factors known to regulate APGP gene expression are also involved in the altered glycosylation. For this purpose, the glycosylation pattern of alpha 1-acid glycoprotein (AGP) as secreted by human hepatocytes, cultured in the presence and absence of dexamethasone and monokines, was studied by crossed affino- (concanavalin A) immunoelectrophoresis (CAIE). The monokines rIL-1 and rIL-6, in the presence of dexamethasone, both stimulated AGP secretion and caused a change in glycosylation towards an increased Con A reactivity, including the appearance of two strongly reactive forms (D and E) normally not present. Dexamethasone alone did not influence either process. When tested in vivo in rats, rIL-6 also induced an increased presence of Con A-reactive forms of AGP in serum. In conclusion, the changes in secretion and glycosylation of AGP as seen during inflammation seem to be mediated by the same factor(s).