Fig. 4: LiSmore enhances the antitumor effect of OT-1 CD8 T cells to reduce melanoma burden in a light-dependent manner.

a Images showing the home-made LED arrays for photostimulation. The blue LED device was installed on the cage lid to enable photoactivation of LiSmore-expressing dendritic cells in the recipient mice. The pictures on the right showed the ambient light density when LED was switched off or turned on. b Schematic illustrating the in vivo testing setup using a B16-OVA melanoma model. 3 × 10⁵ B16-OVA cells were injected (s.c.) in the flank of CD45.1 mice. Mice received PBS, or cGAMP (10 μg/mouse) at days 5, 8, and 11 after tumor inoculation, or were transferred with OVAp-loaded BMDCs expressing Control or LiSmore at day 4, followed by adoptive transfer of CD45.2⁺ OT-1 CD8⁺ T cells at day 5. The mice were then either subjected to photo-stimulation (light) for 7 days (470 nm; ~2 mW/cm²; 30 min ON/OFF cycles for 6 h per day) or shielded from light stimulation (dark). c Representative images of melanoma-bearing mice (left) and isolated tumors (right) for each group on day 21. d Quantification of tumor sizes. n = 5 mice (mean ± SD). Two-sided unpaired Student’s t-test. e Flow cytometry profiles (left) and quantification of mean fluorescence intensity (MFI) of the OVAp/MHC-1 complex (SIINFEKL–MHC-I; middle) and CD80 (right) on the surface of adoptively transferred DCs isolated from tumor-draining lymph nodes (tdLNs) at 18 h in the absence (dark) or presence (light) of photostimulation. Migrated DCs were defined in tdLNs by gating CD45.2⁺GFP⁺ cells. n = 4 independent biological replicates (mean ± SD); one-way ANOVA test. f Flow cytometry analysis of CD69, Ki67 and IFN-γ expression in CD45.2⁺ OT-1 CD8⁺ T cells at 4 h after the final treatment. Left, the gating strategy. Right, representative FACS profiles. g Quantification of CD69⁺CD8⁺ tumor-infiltrating lymphocytes (TILs; left), Ki67⁺CD8⁺ TILs (middle), and IFNγ⁺CD8⁺ TILs (right) in tumors collected from mice shown in panel C. n = 5 mice (mean ± SD). One-way ANOVA.