CD4 and colitis: To test whether the TH1 polarized phenotype of YFP+ naïve‐like cells impacted their ability to induce colitis in this model, we transferred either 25,000 YFP– or YFP+ CD62L+ CD44– CD4+ CD25– T cells into separate Rag2–/– mice and measured disease symptoms (animal, colon, and spleen weights) and cytokine production in colon organ cultures and in unfractionated cells from spleen, mesenteric lymph nodes (mLN), and colon by ELISA.