Abnormal glycosylation of IgG as a clinical parameter in patients with rheumatoid arthritis: Its constitutional analysis by HPLC

To determine the abnormal glycosylation patterns of IgG in patients with rh eumatoid arthritis (RA), we analyzed these oligosaccharide profiles using a recently established high-performance liquid chromatography (HPLC) method. Oligosaccharides of IgG proteins purified from sera of RA patients were la beled with a fluorescent reagent, 2-aminopyridine. The oligosaccharide deri vatives were separated into 12 peaks by HPLC, and compared with those of ag e-matched controls. Serum IgG from patients with RA (RA-IgG) contained a hi gher content of oligosaccharides with bisecting GlcNAc than normal IgG, whi ch was accompanied by an increase in the glycosylation of the bisected olig osaccharides. The ratio of the glycosylation of bisected to nonbisected oli gosaccharides correlated with RA disease activity as well as with its clini cal markers. This ratio reflecting the balance of glycosylation between bis ected and nonbisected oligosaccharides may be a useful clinical parameter t o monitor RA activity.