Figure 7. DFMO targets MDSCs to inhibit tumor growth.

Mice were injected s.c. with 10⁶ B16F10 tumor cells. Depletion of MDSC was achieved by either twice-weekly i.p. injection of (A) 5-Fluorouracil (5-FU) or (B) anti-Gr1 antibodies starting 2 days after tumor challenge (5 mice per group). (C) Splenic Gr1⁺CD11b⁺ MDSCs from B16F10-bearing mice treated with DFMO or dH₂O were injected i.v. into B16-bearing mice at d7 and d14. Mice receiving PBS without MDSCs were controls. Tumor volume was measured and plotted at indicated times (5 mice per group). (D) Flow cytometry analysis of expression of ki67 and Annexin V in gp100-specific tetramer⁺CD8⁺TCRVβ⁺ cells, and absolute number of these tetramer⁺CD8⁺TCRVβ⁺ cells per 10⁶ cells in tumor infiltrates 3d after the initial MDSC transfer (5 mice per group). *, p<0.05; **, p<0.01. Data (mean ± SEM) are representative of 2 independent experiments.