Anti- Human IgG2

Immunoglobulin (Ig) G (IgG) is the predominant of five classes of Ig (IgG, IgA, IgM, IgE, and IgD). Igs differ in heavy chain structure and effector function. IgG1, the largest IgG subclass, represents ~ 60% of IgG and has a half-life of 21 days. Antibody responses to soluble protein and membrane antigens primarily induce IgG1, although polysaccharides and allergens also elicit IgG1 responses. In normal adults, IgG2 represents ~ 30% of serum IgG. IgG2 activates complement less readily than IgG1 and IgG3, has low affinity for Fc receptors on phagocytes (FcγR), crosses the placenta less freely than other IgG subclasses, and has a half-life of 21 days. IgG2 is the predominant antibody that responds to bacterial polysaccharide antigens. Some persons with frequent or severe respiratory tract infection have subnormal IgG2 (< 2 SD below respective means).