The relationship between exposed galactose and N-acetylglucosamine residues on IgG in rheumatoid arthritis (RA), juvenile chronic arthritis (JCA) and Sjögren's syndrome (SS)

The relationship between exposed galactose and N-acetylglucosamine on IgG in RA, JCA and SS was investigated. This was achieved using IgG isolated from serum where the levels of galactose and N-acetylglucosamine (GlcNAc) were detected using biotinylated lectins. Galactose and GlcNAc on IgG from patients with RA and JCA are inversely related, but in contrast, in SS, galactose expression on IgG decreased while GlcNAc expression remained similar to normal levels. Alterations in IgG glycosylation are closely associated with the development of adult and juvenile chronic arthritis and SS, but the changes involved are different in RA compared with SS, suggesting that the precise pattern of exposed sugars is associated with different rheumatological diseases.