Fig. 2

Distribution of galactosylated immunoglobulin G1 (IgG1)- and IgG2-fragment crystallizable (Fc) glycans. a Quantified glycan structures grouped as agalactosylated, (aGal) and galactosylated (Gal) glycans. Glycan nomenclature is according to Royle et al. [35]. The core oligosaccharide structure comprises a biantennary heptasaccharide moiety (A2). Usually, the first sugar unit (an N-acetylglucosamine) is additionally core-fucosylated (e.g., FA2). The biantennary structure can also be transected by an additional N-acetylglucosamine (FA2B). Furthermore, the outer glucosamine units can be elongated with galactoses (FA2Gn, n = 1 or 2), and the galactoses can be further extended with sialic acids (FA2GnSn, n = 1 or 2). b Distribution of galactosylated IgG1- and IgG2-Fc glycans at baseline in healthy control subjects and in patients with early rheumatoid arthritis (RA). The relative distribution (%) of galactosylated Fc glycans differed significantly (p < 0.05) in healthy control subjects compared with patients with early RA and when comparing patients with good response and no response. Collectively, these data demonstrate a changed galactosylation pattern of Fc glycans in RA, with lower proportions of galactosylated glycans than their agalactosylated counterparts. The effect is most pronounced in IgG1. Following false discovery rate correction, p = 0.001 remains significant. C Complement protein, MR Moderate response