A) Experimental design. Female mice of indicated genotypes were treated with DT (1μg via intraperitoneal injection on d0, d1, and d7) and analyzed two weeks after the start of treatment. B-C) Intracellular cytokine staining following 3-hour ex vivo re-stimulation. Pooled data from 4 experiments with n=8 to 25 mice per group. D: H&E staining of colonic sections from indicated genotypes and colitis scores (0–3). Pooled data from two independent experiments with n=5 to 11 mice per group. E: flow cytometry of mast cells in the colonic lamina propria (LP) and intraepithelial (IEL) fractions. Pooled data from 4 (LP) or 3 (IEL) independent experiments with n=8 to 25 mice per group (LP) or n=7 to 15 mice per group (IEL). F: Representative whole-mount immunofluorescence (IF) images of the proximal colon of mice of the indicated genotypes stained with anti-Mcpt1 (red) and anti-Ep-Cam (blue). Scale bars, 50μm. Scale bar of inset below, 10μm. G: Total CD4 and CD8 T cell counts in the spleen and colonic LP analyzed by flow cytometry. Pooled data from 8 experiments with n=16 to 31 mice per group. P-values from Brown-Forsythe and Welch ANOVA (*:p<0.05, **p<0.01, ***: p<0.001, ****: p<0.0001). See also Figure S5.