Interferon (IFN)-gamma is an antiviral and antiparasitic agent produced by CD4+/CD8+ lymphocytes and natural killer cells that undergo activation by antigens, mitogens or alloantigens. IFN-gamma production modulates T cell growth and differentiation and inhibits the growth of B cells. Synthesis of IFN-gamma is inducible by IL-2, FGF and EGF. The active form of IFN-gamma is a homodimer with each subunit containing six helices. The dimeric structure of human IFN-gamma is stabilized by non-covalent interactions through the interface of the helices. IFN-gamma tranlsated precursor is 166 amino acids, including the 23 amino acid secretory sequence. Multiple forms exist due to variable glycosylation and under non-denaturing conditions due to dimers and tetramers.