TNF and infection: Thus, it seems that the outcome of infection could depend on whether the host mounts primarily Th-1 inflammatory cytokines (especially IFN-γ, TNF-α, and IL-12) which are crucial factors in the initiation of immune protection or Th-2 inflammatory cytokines facilitate the persistence of parasites through downregulating Th1 immune response to leishmania infection [21, 95].