Response to Oswald et al.: ST6Gal1 in plasma is dispensable for IgG sialylation

The presence or absence of terminal sialic acid residues in the sugar moiety attached to the Fc-domain of IgG molecules modulates IgG activity and is associated with autoimmune or infection related inflammation. In a recent paper, Oswald and colleagues suggest that IgG sialylation may occur post IgG secretion from plasma cells, which would be a major issue for therapeutic antibodies injected into patients. In contrast, we argue that previous work rather demonstrates that IgG sialylation occurs within B cells and that the experimental system used by the authors is not suitable to address this critical question.

Automated summary

The presence or absence of terminal sialic acid residues in the sugar moiety attached to the Fc-domain of IgG molecules plays a role in modulating IgG activity and is associated with autoimmune or infection-related inflammation. Recent findings by Oswald and colleagues propose that IgG sialylation may occur post IgG secretion, which has implications for therapeutic antibodies. However, we argue that previous research suggests that IgG sialylation actually occurs within B cells and question the suitability of the experimental system employed by the authors to address this question.