Interferon-gamma (IFNγ), exerts a wide range of immunoregulatory activities Mature mouse IFN-gamma exists as a noncovalently linked homodimer of 20-25 kDa variably glycosylated subunits. IFNγ binds IFN-γ receptors (IFNγ R1 and IFNγ R2), which are expressed on most immune cells, to activate the JAK-STAT pathway. IFNγinduced signaling increases the expression of class 1 major histocompatibility complex (MHC) molecules. IFNγ is produced by a variety of immune cells under inflammatory conditions, notably by T cells and NK cells. It plays a key role in host defense by promoting the development and activation of Th1 cells, chemoattraction and activation of monocytes and macrophages, and up-regulation of antigen presentation molecules. It also exhibits antiviral, antiproliferative, and apoptotic effects.