INVESTIGATION INTO THE CONCANAVALIN-A REACTIVITY, FUCOSYLATION AND OLIGOSACCHARIDE MICROHETEROGENEITY OF ALPHA(1)-ACID GLYCOPROTEIN EXPRESSED IN THE SERA OF PATIENTS WITH RHEUMATOID-ARTHRITIS

alpha(1)-Acid glycoprotein (AGP) exists as an heterogeneous population of glycosylated variants (glycoforms) in plasma. The concentration of AGP increases some 2-5 fold in certain pathophysiological states exem plified by the chronic inflammatory disease, rheumatoid arthritis (RA) . Moreover, the expressed glycosylation pattern alters in such conditi ons, indicating functional significance that is likely to be related t o the oligosaccharide heterogeneity. We have investigated the heteroge neity of AGP glycosylation using the technique of high pH anion-exchan ge chromatography (HPAEC). AGP was isolated from the blood of RA suffe rers, partially separated by Concanavalin A (Con A) affinity chromatog raphy into bound and non-bound fractions and was enzymatically deglyco sylated. Chromatography on the pellicular HPAE resin at pH 13 separate d the released oligosaccharides and allowed a comparison of profiles i n terms of branching and fucosylation. Results demonstrate an abnormal RA AGP glycosylation, with a tendency towards tri- and tetra-antennar y oligosaccharides and enhanced fucosylation, in addition to the possi ble existence of penta-sialylated RA AGP glycoforms.