During the acute ileitis caused by oral inoculation of certain mouse strains with the protozoan parasite Toxoplasma gondii, there is accumulation of Ly6Chi monocytes, which display the same behavior as those arriving into the DSS-inflamed colon, including the production of the pro-inflammatory cytokines TNFα and IL-12, and reactive nitrogen species 125. Here, TNF is linked to Crohn ileitis.