Mouse Ifng is a secreted protein which belongs to the type I I (or gamma) interferon family. IFNG is produced by lymphocytes and activated by specific antigens or mitogens. In addition to having antiviral activity, IFNG also has important immunoregulatory functions. It is a potent activator of macrophages and has antiproliferative effects on transformed cells. It can potentiate the antiviral and antitumor effects of the type I interferons. Genetic variation in IFNG is associated with the risk of aplastic anemia (AA) which is a rare disease in which the reduction of the circulating blood cells results from damage to the stem cell pool in bone marrow. In most patients, the stem cell lesion is caused by an autoimmune attack. T-lymphocytes, activated by an endogenous or exogenous, and most often unknown antigenic stimulus, secrete cytokines, including IFN-gamma, which would in turn be able to suppress hematopoiesis.