SHP-1–deficient T cells are pathogenic and able to induce colitis. CD4⁺CD25⁻ CD45RB^hi T cells (5 × 10⁵) isolated from +/+ or me/+ mice were transferred into rag1^−/− recipients. (A) Representative colon segments of recipient mice 7 to 8 weeks after adoptive T-cell transfer (+/+, me/+, and PBS, H&E, original magnification ×200). The arrow points to a giant cell among inflammatory cells. (B) Pathologic scoring of colon segments from recipient mice 7 to 8 weeks after adoptive T-cell transfer (+/+ vs me/+, P = .5, not significant; +/+ vs PBS, P = .001; me/+ vs PBS, P = .02). (C-D) Numbers of IL-17A/F⁺ T cells within the CD4⁺ compartment isolated from the lamina propria (C, +/+ vs me/+, P = .5, not significant) and Peyer patches (D, +/+ vs me/+, P = .7, not significant) of the indicated donor-derived populations 7 to 8 weeks after transfer. Data are representative of 3 independent experiments with multiple mice for each genotype per experiment.