Interferon gamma (IFNγ) is a dimerized soluble cytokine that is predominately produced by natural killer and natural killer T cells during the innate immune response and by T cells once antigen specific immunity develops. IFNγ is crucial for immunity against intracellular pathogens and for tumor control. Release of IFNγ is controlled mostly by the cytokines IL-12 and IL-18. Serum IFNγ levels have been shown to be elevated in active cases of systemic lupus erythematosus (SLE) and may be associated with the development of autoimmune diseases like SLE.