Figure 2.

Local expression of IL-21 potently inhibited B16 melanoma growth in mice. (A) Schematic representation of the lentiviral vector used to create stable cell lines expressing individual immunomodulatory molecule. (B, C) Impacts of local expression of different immunomodulatory molecules on the B16 melanoma development in mice. 5×10⁵ of the indicated cells were subcutaneously injected into the right flank of syngeneic mice, followed by measurement of tumor size (B) and survival curves (C) (n=5, **p<0.01, log-rank test). Data are representative of two independent experiments. (D–F) Effects of local expression of IL-21 on tumor-infiltrating lymphocytes (TILs). Mice were inoculated subcutaneously with 5×10⁶ B16-pHAGE cells or B16-mIL21 cells. For the FACS analysis of TILs, B16-mIL21 tumors were assayed 21 days after inoculation while the B16-pHAGE tumors were assayed when end points were reached (animal death or tumor volume of ≥2000 mm³). (D) Frequency of CD45^high lymphocytes. (E) Frequencies of CD3⁻NK1.1⁺ NK cells, CD3⁺ T lymphocytes, CD4⁺ T lymphocytes, CD8⁺ T lymphocytes, effector memory (CD44⁺CD62L⁻) T cells and (F) Tregs. Due to the scarcity of Tregs, for their measurements, the samples from mice receiving the same graft was pooled. n=6 per group; data are representative of two independent experiments; **p<0.01, ***p<0.001, Student’s t-test.