The carbohydrate switch between pathogenic and immunosuppressive antigen-specific antibodies

Area of Science:

• Immunology
• Glycobiology

Background:

• Immunoglobulin G (IgG) antibodies possess a conserved N-glycosylation site influencing effector functions.
• Fc glycans, including core structures and terminal modifications like galactose and sialic acid, modulate IgG's pro- or anti-inflammatory roles.

Purpose of the Study:

• To explore the distinct roles of differentially glycosylated IgG antibodies in immune responses.
• To highlight the potential of antigen-specific galactosylated and sialylated IgGs as therapeutic agents for autoimmune and allergic diseases.

Main Methods:

• Review and synthesis of existing research on IgG glycosylation and its functional implications.
• Analysis of the association between IgG glycoforms and inflammatory versus tolerance-inducing immune states.

Main Results:

• Non-galactosylated (G0) IgG is linked to pro-inflammatory responses in autoimmune conditions like rheumatoid arthritis.
• Sialylated IgG mediates anti-inflammatory effects, as observed with intravenous immunoglobulin (IVIG) therapy.
• Antigen-specific G0 IgGs are induced by pro-inflammatory responses, whereas galactosylated and sialylated IgGs are associated with tolerance.

Conclusions:

• Differential IgG glycosylation is critical for mediating specific immune effector functions.
• Antigen-specific galactosylated and sialylated IgGs represent a promising therapeutic strategy for re-establishing self-tolerance in autoimmune and allergic patients.