B7-H3^−/− donor T cells have increased GVHD-induced gut injury. (A) BALB/c mice were lethally irradiated and infused with 10⁷ B6-WT BM and 1 × 10⁶ B6-WT or B7-H3^−/−-purified T cells. On day 21, 16 mg of FITC-dextran was administered orally to mice, and serum levels were measured 4 hours later (n = 4). One experiment was performed. (B) BALB/c mice were lethally irradiated and infused with 10⁷ B6 BM and 1 × 10⁶ B6-WT or B7-H3^−/−-purified T cells. Mice were euthanized on day 21 after transplant, and intraepithelial lymphocytes were analyzed for Ki-67 and annexin V expression (n = 4). One experiment was performed. (C) BALB/c mice were lethally irradiated and infused with 10⁷ B6-WT BM and 1 × 10⁶ B6-WT or B7-H3^−/−- purified T cells. Mice were euthanized on day 21 after transplant, and intraepithelial lymphocytes and lamina propria lymphocytes were analyzed for CD4 or CD8 and IFN-γ, TNF-α, IL-2, or IL-17 coexpression (n = 4). One experiment was performed. *P < .05; **P < .01; ***P < .001.