Figure 9.

VISTA overexpression on tumor cells overcomes protective antitumor immunity. MCA105 tumor cells overexpressing VISTA or RFP control protein were generated by retroviral transduction and sorted to homogeneity. To generate protective immunity, naive mice were vaccinated with irradiated MCA105 tumor cells subcutaneously on the left flank. (A) Vaccinated mice were challenged 14 d later with live MCA105VISTA or MCA105RFP tumor cells subcutaneously on the right flank. Tumor growth was monitored every 2 d. Tumor size is shown as mean ± SEM. Shown are representative results from three independent repeats. (B) Vaccinated mice were either untreated or depleted of both CD4⁺ and CD8⁺ T cells by mAbs before live tumor challenge. Tumor size was monitored as in A and shown as mean ± SEM. Shown are representative results from two independent repeats. For all experiments, ratios indicate the number of tumor-bearing mice among total number of mice per group. The statistical differences (p-values) were assessed with an unpaired Mann-Whitney test.