Aglycosylated immunoglobulin G1 variants productively engage activating Fc receptors. Proc. Natl. Acad. Sci. USA. 105: 20167-20172

Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 01/2009; 105(51):20167-72. DOI: 10.1073/pnas.0809257105
Source: PubMed


Immunoglobulin G plays a vital role in adaptive immunity and antibody-based therapy through engagement of its Fc region by the Fc gamma receptors (Fc gammaRs) on immune cells. In addition to specific protein-protein contacts, N-linked glycosylation of the IgG Fc has been thought to be essential for the recognition of Fc by Fc gammaR. This requirement for the N-linked glycan has limited biomanufacture of therapeutic antibodies by restricting it to mammalian expression systems. We report here aglycosylated Fc domain variants that maintain engagement to Fc gammaRs, both in vitro and in vivo, demonstrating that Fc glycosylation is not strictly required for the activation of immune cells by IgG. These variants provide insight into how the N-linked glycan is used biologically in the recognition of Fc by Fc gammaRs, as well as represent a step toward the production in alternative expression systems of antibody-based therapeutics capable of eliciting immune effector functions.

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    • "In this study, we evaluate the contribution of Fc N-glycosylation to Fc structure and FcgRIIIa affinity to determine how the Fc N-glycan contributes to Fc activity and, in so doing, define the mechanism behind a previously unknown role for N-glycans in biology. We utilized two well-described Fc variants that are reported to show no measurable affinity for FcgRIIIa: (glycosyl) Fc D265A (Baudino et al., 2008; Bournazos et al., 2014; Clynes et al., 2000; Lund et al., 1995, 1996) and (aglycosyl) Fc T299A (Lazar et al., 2009; Sazinsky et al., 2008; Subedi et al., 2014). Here, we report the identification of IgG1 Fc features that are stabilized by N-glycosylation, and in the stabilized state contribute to FcgRIIIa binding. "
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    • "Igawa). number of reports about engineering the heavy chain Fc region to improve the binding affinity for Fc␥Rs by methods such as afucosylation of the N-linked glycan attached to Asn297 (Shields et al., 2002; Shinkawa et al., 2003) or symmetrically introducing amino acid substitutions into the heavy chain Fc region with or without the N-linked glycan attached to Asn297 (Green et al., 2002; Jung et al., 2010; Lazar et al., 2006; Richards et al., 2008; Sazinsky et al., 2008; Stavenhagen et al., 2007). These engineered Fc variants enhanced the binding affinity for Fc␥RIIa and Fc␥RIIIa or improved the ratio of activating Fc␥R binding to inhibitory Fc␥R binding (A/I ratio), which resulted in enhanced ADCP and ADCC activity. "
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