CHROMATOGRAPHIC INVESTIGATION OF THE GLYCOSYLATION PATTERN OF ALPHA-1-ACID GLYCOPROTEIN SECRETED BY THE HEPG2 CELL-LINE A PUTATIVE MODEL FOR INFLAMMATION

In certain pathophysiological conditions, such as rheumatoid arthritis , there are alterations in the glycosylation pattern of the acute phas e protein, alpha-1-acid glycoprotein (AGP). These changes are likely t o be functionally significant, however, verification of the latter rol e requires a system which reflects in vivo glycosylation changes in AG P and also produces sufficient quantities of the protein for further s tudy. The human hepatoma cell line HepG2 is documented as displaying a shift in the glycosylation pattern of glycoproteins from normal state to acute phase after stimulation with inflammatory mediators. We have Isolated AGP from the culture medium of HepG2 cells both before and a fter stimulation with a cytokine preparation and analysed the glycosyl ation pattern of each preparation, after enzymatic release, by high pH anion-exchange chromatography. Before stimulation, the glycosylated p opulation was similar to a profile of AGP isolated from normal plasma; however, cytokine stimulation resulted in a shift to a profile which was consistent with that of AGP from a rheumatoid arthritis sufferer. Thus a HepG2 cell culture system is capable of being a crude model of the changes in glycosylation of acute phase proteins although it has a tendency to produce oligosaccharide chains which are not fully sialyl ated.