Figure 1. Antitumor immunity of IL-12–engineered pmel-1 CD8⁺ T cells (IL-12 cells) is not dependent on type I self polarization but does require an endogenous response to secreted IL-12.

(A) Representative intracellular flow cytometry plot for IL-12 expression in WT or Il12rb2^–/– CD8⁺ cells. (B) Representative histogram for CD62L, IL-2Rα, IL-7Rα, and Sca-1 expression in WT or Il12rb2^–/– IL-12 cells. (C) Intracellular staining for IFN-γ and TNF-α in WT or Il12rb2^–/– IL-12 cells stimulated with PMA/ionomycin. All flow cytometry data in A–C are representative of at least 3 independent experiments. Numbers represent percentage of cells in each quadrant. (D) Tumor treatment with 10⁵ WT or Il12rb2^–/– IL-12 cells transferred into sublethally irradiated (5-Gy TBI) C57BL/6 mice bearing 10-day established subcutaneous B16 tumors (n = 5). All data are expressed as mean ± SEM and are representative of 2 independent experiments. *P < 0.05, Wilcoxon’s rank-sum test compared with no treatment (NT) control. (E) Antitumor immunity of 10⁵ WT IL-12 cells transferred into sublethally irradiated WT or Il12rb2^–/– C57BL/6 mice bearing subcutaneous B16 tumors established for 10 days. All data are expressed as mean ± SEM and are representative of 2 independent experiments. *P < 0.05, Wilcoxon’s rank-sum test compared with no treatment control; ^ΨP < 0.05, compared with WT IL-12 cells in Il12rb2^–/– host.