In murine experimental models, protection against cutaneous leishmaniasis is associated with a robust T helper (Th) 1 (Th1) cell immune response and the production of interferon (IFN) gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α), whereas susceptibility is associated with a Th2 response involving IL-10 and IL-4. This evidence concerns the gene TNF and cutaneous leishmaniasis.