IBD-inducing potential from naive IL-7^–/– CD4⁺ T cells. (A) Weight loss expressed as a percentage of initial body weight at the indicated times after injection of naive CD4⁺ T cells (groups of 3-5 mice). (▪) indicates noninjected mice; (♦, ⋄), Rag-2^–/– recipients of mixtures of naive CD4 cells with B6 or IL-7^–/– CD4⁺CD25⁺ T cells, respectively; (•, ○), Rag-2^–/– IL-7^–/– recipients of naive wild-type or IL-7^–/– mice, respectively; (▴, ▵) Rag-2^–/– recipients of naive wild-type or IL-7^–/– mice, respectively. (B-E) H&E histologic analysis of the colon of recipient mice. (B) Naive IL-7^–/– T cells transferred into Rag-2^–/– recipients. Inflammatory cells largely infiltrate into the submucosa and partially into the muscularis with microabscess and mucin depletion (stage 3). (C) Naive wild-type T cells transferred into Rag-2^–/– recipients. Transmural infiltration with marked inflammatory cells, epithelial erosion, and mucin depletion (stage 4). (D) Naive IL-7^–/– wild-type T cells transferred into Rag-2^–/– IL-7^–/– recipients. Diffuse inflammatory infiltration into the submucosa with moderate mucine depletion (stage 2). (E) Naive wild-type T cells transferred into Rag-2^–/– IL-7^–/– recipients. Diffuse inflammatory infiltration into the submucosa with moderate mucine depletion (stage 2). The lesions are less severe with wild-type donors (E). (F) Naive wild-type CD4⁺ T cells transferred with IL-7^–/– CD4⁺CD25⁺ T cells. No infiltration is observed (stage 0).