However, in the absence of macrophages FoxP3- T cells caused demyelination; 2) In both models, macrophages played a critical role in prevention of autoimmunity; 3) Either suppression of macrophages by IL-2 or their absence caused an imbalance of T cells and the development of autoaggressive T cells; and 4) Adoptive transfer of macrophages over-expressing IL-12p70 or IL-12p40, but not IL-12p35, blocked HSV-1 induced CNS demyelination in a dose-dependent manner. The gene discussed is IL2; the disease is Autoimmunity.