IL4 and infection: Analysis of cytokine production by macrophages showed that infection with L. amazonensis, L. donovani or T. cruzi only induces very low intensity secretion of inflammatory cytokines such as IL-6, IL-8, and TNF (Fig 3), while other cytokines where undetectable (IL-2, IL-4, IL-5 and IFN-γ, indicating that macrophages do not mount an effective inflammatory response to infection with these parasites.