Purified IgG may be used as a reference antigen, standard, blocking agent or coating protein in a variety of immunoassays including ELISA, dot immunobinding, Western immunoblotting, immunodiffusion, immunoprecipitation and immunoelectrophoresis. Other applications include starting materials for the preparation of immunogens and solid-phase immunoadsorbents.
IgG consists of four isotypes IgG1, IgG2, IgG3 and IgG4. It contains four polypeptide chains, made of two identical 50 kDa γ heavy (H) chains and two identical 25 kDa κ or λ light (L) chains, which are connected by inter-chain disulfide bonds.
IgG mediates transplacental transport and participates in the secondary immune response. IgG activates the classical pathway of the complement system. It neutralizes virus particles and toxins. IgG plays a key role in antibody dependent cell-mediated cytotoxicity (ADCC) and phagocytosis. It might be linked to allergy. It has the longest serum half life.
