IFN-gamma

Interferon-gamma (IFN-gamma) is a type II interferon and is expressed predominantly by CD8+ and CD4+ T cells, and natural killer (NK) cells. IFN-gamma acts as a potent activator of antigen presenting cells as well as inducing expression of IL-12, which in turn promotes a TH1 cell mediated immune response for clearing of viral and microbial infections. IFN-gamma activates non-specific tumoricidal activity in macrophages in addition to enhancing the cytotoxicity of NK cells. IFN-gamma can also directly inhibit proliferation of transformed cells or potentiate the antiviral and anti-tumor effects of the type I interferons. IFN-gamma exists as a non-covalently associated homodimer and functions by binding the IFN-gamma receptor present on T cells, B cells, macrophages, neutrophils and NK cells as well as non-immune somatic cells such as endothelial cells, epithelial cells and fibroblasts. Structurally, IFN-gamma is synthesized as a precursor glycoprotein with 2 potential N-glycosylation sites with a molecular mass of between 20 and 25 kDa depending on the extent of glycosylation.