Distribution of glycosylation abnormality among serum IgG subclasses from patients with rheumatoid arthritis

IgG from patients with rheumatoid arthritis possess significantly fewer galactose residues in its sugar chains. We made an attempt to analyze the distribution of a galactosylation defect among IgG subclasses by immunoassay using PVL, a recently described lectin specific for N-acetylglucosamine (GlcNAc). A distinct difference between RA and normal controls was present in IgG2 (P = 0.0007). A less remarkable but significant difference was seen in IgG1 (P = 0.0118) and in IgG4 (P = 0.022). A significant difference was not observed in IgG3 (P = 0.169). The possible relationship between such a glycosylation abnormality and RF production was discussed.