Interferon gamma (IFN-γ) is a dimerized soluble cytokine that is the only member of the type II class of  interferons. IFN-γ, or type II interferon, is a cytokine that is critical forinnate and adaptive immunity against viral, some bacterial and protozoal infections. IFN-γ is an important activator of macrophages and inducer of Class II major histocompatibility complex (MHC) molecule expression. Aberrant IFN-γ expression is associated with a number of autoinflammatory and autoimmunediseases. The importance of IFN-γ in the immune system stems in part from its ability to inhibit viral replication directly, and most importantly from its immunostimulatory and immunomodulatory effects. IFN-γ is produced predominantly by natural killer (NK) and natural killer T (NKT) cells as part of the innate immune response, and by CD4 Th1 and CD8 cytotoxic T lymphocyte (CTL) effector T cells onceantigen- specific immunity develops.
The role of IFN-γ as a disease marker has been demonstrated for a number of different pathological situations including infections, autoimmune diseases, transplant rejection, allergy and diabetes.