CD4 and digestive system infectious disorder: CD4+ T cells play a central role in immune response to intestinal infection with C. rodentium via the production of cytokines required for host resistance to this pathogen, including IL-17, IL-22 and IFN-γ, and they have been shown to be a main source of antigen-specific induction of IFN-γ during intestinal infection with this bacterium [17].