Figure 2.

OX40 expression on T reg cells is required to suppress T cell induced colitis. RAG^−/− mice received WT CD4⁺CD45RB^hi T cells alone (no T_R), or in combination with WT or OX40^−/− CD4⁺CD25⁺ T reg cells (T_R). (A) Mean weight of six animals per group (± SEM). (B) Colitis score at 8 wk. An additional control group showed that OX40^−/− T reg cells do not induce colitis by themselves. (C) Photomicrographs of mid-colon sections. Bar, 100 µm. (D) Number of colonic IFN-γ⁺ and IL-17⁺CD4⁺ T cells, neutrophils (CD11c⁻CD11b^hiGr1^hiSSC^hi) and monocytes/macrophages (CD11c⁻CD11b^hiGr1^intSSC^lo) at 8 wk. Each point represents an individual mouse and horizontal bars represent group means (B and D). Results are representative of three independent experiments.