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.

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 ...

The IgG3, though of relatively low affinity, allows IgG-mediated defences to join IgM-mediated defences in clearing foreign antigens. Subsequently, higher affinity IgG1 and IgG2 are produced. The relative balance of these subclasses, in any immune complexes that form, helps determine the strength of the inflammatory processes that follow.

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.

2024年1月23日 · IgG3. IgG3 comprises around 5 to 10% of total IgG and has a molecular weight of 170 kDa. They play a major role in the immune responses against protein or polypeptide antigens which are T dependent antigens. The IgG3 are particularly good opsonins and mediators of ADCC because FcγRs bind sIgG3 antibodies with high affinity.

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.

2025年3月20日 · IgG3 is the most potent activator of complement among the IgG subclasses, making it highly effective in immune complex formation and complement-dependent cytotoxicity. Despite its strong effector functions, IgG3’s short half-life limits therapeutic applications. Some engineered monoclonal antibodies aim to extend its stability while ...

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.