What are IgG deficiencies? An IgG deficiency is a health problem in which your body doesn’t make enough Immunoglobulin G (IgG). People with IgG deficiency are more likely to get infections. When your body feels it is under attack, it makes special proteins called immunoglobulins or antibodies. These antibodies are made by the plasma cells.

Of the five immunoglobulin isotypes, immunoglobulin G (IgG) is most abundant in human serum. The four subclasses, IgG1, IgG2, IgG3, and IgG4, which are highly conserved, differ in their constant region, particularly in their hinges and upper CH2 ...

Understanding the molecular and functional properties of IgG3 may facilitate the development of improved Ab-based immunotherapies and vaccines against infectious diseases.

IgG is divided into four subclasses: IgG1, IgG2, IgG3, and IgG4. People are said to have an IgG subclass deficiency when they lack or have very low levels of one or two IgG subclasses, but have normal levels of other immunoglobulins.

Individuals with IgG subclass deficiency are defined as having recurrent infections, persistently low levels of one or more IgG subclasses, and normal concentrations of total IgG, IgM, and IgA. IgG2 or IgG3 deficiencies are the most common IgG subclass deficiencies.

Evidence suggests that the IgG3 hinge may allow targeting of antigens or epitopes less suited to ligation by other IgG types, with the potential to more effectively stimulate cellular activity via Fcɣ receptors.

2019年2月8日 · IgG3 has been associated with enhanced control or protection against a range of intracellular bacteria, parasites, and viruses. IgG3 Abs are potent mediators of effector functions, including enhanced ADCC, opsonophagocytosis, complement activation, and neutralization, compared with other IgG subclasses.

2023年7月7日 · IgG3 forms elevated hexameric Fc platforms that extend above the protein corona to maximise binding to receptors and the complement C1 complex, which here adopts a unique protease conformation...

IgG1 and IgG3 respond to protein antigens. They are T-dependent antigens; IgG2 and IgG4 respond to polysaccharide antigens, which are T-independent antigens. IgG functions by opsonizing microbes for phagocytosis and killing, activating the complement cascade, and neutralizing many bacterial endotoxins and viruses.

2022年6月24日 · IgG3 comprises around 5 to 10% of total IgG and plays a major role in the immune responses against protein or polypeptide antigens. Comprising usually less than 4% of total IgG, IgG4 does not bind to polysaccharides.