CD4 and infection: ,36, 37, 38 Mouse models investigated comprise commonly used models of IBD: (1) the TnfΔARE mouse model of ileitis; (2) IL-10-deficient mice as model of colitis; (3) an adoptive T cell transfer model of colitis, Rag2-/- mice reconstituted with CD4+ CD25- T cells; and (4) an infection model using Citrobacter rodentium.