Abstract
The glycoprotein immunoglobulin G (IgG) is a major effector molecule of the humoral immune response in man and accounts for about 75% of the total immunoglobulins in plasma of healthy individuals. Antibodies of the IgG class express their predominant activity during a secondary antibody response. In comparison to antibodies of the IgM class, IgG antibodies have a relatively high affinity and persist in the circulation for a long time. Whereas all other Ig isotypes contain multiple glycosylation sites in the antibody constant and variable domains, IgG molecules have only one sugar moiety attached to each of the CH2 domains in the IgG constant fragment. This sugar moiety consists of a heptameric core structure of N-acetylglucosamine and mannose residues with variable additions of terminal (galactose and sialic acid) and branching (fucose and N-acetylglucosamine) residues. In the serum more than 30 different IgG glycoforms can be identified, and the pattern of IgG glycosylation can change during inflammatory responses. Removal of this sugar moiety abrogates IgG function, and certain IgG glycoforms have been demonstrated to have enhanced effector functions, suggesting that regulation of IgG glycosylation may be a means of modulating IgG activity.
Original language | English |
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Title of host publication | Molecular and Cellular Mechanisms of Antibody Activity |
Publisher | Springer New York |
Pages | 85-112 |
Number of pages | 28 |
Volume | 9781461471073 |
ISBN (Electronic) | 9781461471073 |
ISBN (Print) | 1461471060, 9781461471066 |
DOIs | |
Publication status | Published - 1 Jul 2013 |
Keywords
- Autoimmune disease
- Humoral immunity
- IgG
- IgG subclasses
- Immunoglobulins
- Opsonisation
- Phagocytosis