Immunoglobulin G3

Athens Research

Immunoglobulin G3

9

Inflammation, Biotherapeutics, In Vitro Diagnostic, Wiskott-Aldrich syndrome, Autoimmune Diseases, Infection

Research Use Only

≥95% by SDS-PAGE

Serum IgG3, constituting ~6% of total IgG, is distinguished by an elongated 62-amino-acid hinge region stabilized by 11 disulfide bonds, conferring unmatched flexibility for antigen engagement and effector function activation. This subclass exhibits potent complement activation via C1q binding and high-affinity interactions with FcgammaRI/III receptors, surpassing IgG1 in triggering antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis. Its extended hinge enhances spatial tolerance for antigen binding, enabling superior neutralization of enveloped viruses like HIV and CHIKV. IgG3 deficiency (less then0.3 g/L) correlates with Wiskott-Aldrich syndrome, systemic lupus erythematosus (SLE), and recurrent bacterial/viral infections due to impaired immune complex clearance. In SLE models, IgG3 deposits drive glomerulonephritis via FcgammaR-mediated neutrophil activation, while its deficiency attenuates renal damage. Paradoxically, early IgG3 responses in acute infections (e.g., CHIKV) correlate with severe initial symptoms but prevent chronic arthralgia by rapid viral clearance. Clinically, IgG3’s short half-life (7 days vs. IgG1’s 21 days) stems from Arg435-mediated FcRn competition, though the H435 allotype extends half-life for therapeutic use. Anti-HIV IgG3 antibodies peak within 4–5 months post-infection, serving as transient biomarkers for recent exposure6. Hinge-length polymorphisms (3 vs. 4 repeats) influence COVID-19 severity, with shorter hinges impairing viral neutralization and increasing mortality risk. Engineered IgG3 variants with stabilized hinges enhance phagocytosis 3-fold, offering promise for antibody therapeutics targeting intracellular pathogens.

more then 1 year

Source human plasma non-reactive for HBsAG, anti-HCV, anti-HBc, and negative for anti-HIV 1 & 2 by FDA approved tests.

+2 - 8° C

12352202