Bcl11b^F/F/CD4-Cre mice develop wasting disease, caused by IBD, associated with massive infiltrations of CD4⁺ T cells in the colon. (A) Weights of Bcl11b^F/F/CD4-Cre and WT mice were recorded starting at 4 wk of age (n = 6 mice per group). Asterisks indicate statistical significance determined by unpaired two-tailed Student’s t test (*, P < 0.05). (B) Representative colon gross anatomy of Bcl11b^F/F/CD4-Cre and WT mice 12–16 wk of age. (C) Representative H&E staining of colon sections of a similar area along the length of the colon from Bcl11b^F/F/CD4-Cre and age- and sex-matched WT mice at 15–16 wk of age. The bottom panel shows a higher magnification image of the marked areas in the KO section. (D) Alcian blue counterstained with Nuclear Fast red of colon sections from Bcl11b^F/F/CD4-Cre and WT mice, indicating in blue mucus-producing goblet cells. Bars, 100 µm. (B–D) Data are representative of at least 10 pairs of mice. (E) Histological scores of colitis at 15–16 wk of age, using the criteria described in Table S1. P (evaluated by unpaired two-tailed Student’s t test) = 4.52 × 10⁻⁸. The error bar indicates SD. (F) Absolute numbers of total cells in the colon LP and epithelium (IEL) of Bcl11b^F/F/CD4-Cre versus WT mice. (G) Absolute numbers of CD4⁺ T cells present in the colon LP and epithelial compartment (IEL). (F and G) Asterisks indicate statistical significance as determined by unpaired two-tailed Student’s t test (*, P < 0.05). Horizontal bars indicate the mean. (H and I) Frequencies of CD4⁺ and CD8⁺ T cells among the colon LP lymphocytes (H) and IELs (I) evaluated by flow cytometry. (E–I) Data are derived from four to five mice per group.