Interferons are best known for their critical functions in host defense mechanisms. The type I Interferons include the IFN-alpha family, IFN-beta, -omega, -kappa and Limitin and are important for marshalling the immune response to viral infection. The type II interferon group includes only IFN-gamma. IFN-gamma is a multifunctional cytokine that exerts aniti-proliferative, immunoregulatory, and proinflammatory effects improtant for numerous aspects of the immune response.