c-MPL signaling in T cells significantly enhances antitumor function in a leukemia xenograft model. (A) Experimental set up. (B) Kaplan-Meier survival analysis. Survival of hTPOtg-RAG2^−/−γc^−/− mice, injected with BV173-ffLuc⁺ cells and treated with control T cells (n = 7), TCR⁺ T cells (n = 9), TCR⁺c-MPL⁺ T cells and PBS injections (n = 14), TCR⁺c-MPL⁺ T cells and rhTPO injections (n = 10). Results combined from 3 independent experiments. Overall survival: P = .004. TCR vs TCR⁺c-MPL⁺ (PBS injected): P = .27. TCR vs TCR⁺c-MPL⁺ (rhTPO injected): P = .001. TCR⁺c-MPL⁺ (PBS injected) vs TCR⁺c-MPL⁺ (rhTPO injected): P = .07. (C) 3 representative mice/group imaged over time by BLI; color scale 5 × 10³ to 5 × 10⁴ p/sec/cm²/sr. (D) Summary of BLI data by treatment condition, results combined from 3 independent experiments, mean ± SD. Control T cells (n = 7, lime green circles solid lines), TCR⁺ T cells (n = 9, lavender squares solid lines), TCR⁺c-MPL⁺ T cells (PBS injected; n = 14, blue triangles up solid lines), TCR⁺c-MPL⁺ T cells (rhTPO injected; n = 10, blue triangles down dotted lines). TCR vs TCR⁺c-MPL⁺ (PBS injected): P = .004. TCR vs TCR⁺c-MPL⁺ (rhTPO injected): P = .0005. TCR⁺c-MPL⁺ (PBS injected) vs TCR⁺c-MPL⁺ (rhTPO injected): P = .088. Statistics was performed using the Student t test on log AUC at week 4 compared with week 1.