Combination of Ad-USP18 and antigen-specific CTLs in subcutaneous B16 melanoma therapy. 1 × 106 B16-OVA-GFP or B16-OVA-USP18 cells were subcutaneously inoculated into C57BL/6 mice (n = 5). Tumor MHC class-I and PD-L1 expression was analyzed by flow cytometry (A). Antigen-specific CTLs in the spleen and tumor were analyzed as OT-1 tetramer-positive CD8+ T cells (B). 1 × 106 B16-OVA cells were subcutaneously inoculated into CD45.1+ C57BL/6 mice. At day 5, tumor-bearing mice were treated with 5 × 106 activated CD45.2+ OT-1 cells (intravenous) and intra-tumor injection of Ad-GFP or Ad-USP18 (1010 pfu in 50 μl). B16-OVA tumor growth was monitored. (C). Effector CD45.2+ CD8+ T-cell persistence was measured 15 days after tumor inoculation (D). 1 × 106 B16 cells were subcutaneously inoculated into C57BL/6 mice. The tumor-bearing mice were treated with 5 × 106 activated pmel-1+ CTLs (intravenous) along with intra-tumor injection of Ad-GFP or Ad-USP18 (1010 pfu in 50 μl) with or without dendritic cell vaccination. B16 tumor growth was monitored after CTL and Ad-USP18 treatment (E).