Figure 4.

SVX therapeutic efficacy against tumor cells in CD8-depleted mice. BALB/c mice (8 mice per group) were engrafted s.c with hCT26 (A,C) or hA20 tumor cells (B,D). When tumors reached 10 mm², mice were s.c injected with PBS, or were immunized with SVX + CpG/IFA and received a boost 1 week later without adjuvant (SVX). (A,B) Groups of vaccinated mice engrafted with hCT26 (A) or hA20 tumor cells (B) were depleted of CD8⁺ T cells, using anti-CD8 mAbs (100 μg) injected intra-peritoneally (i.p) once a week, starting 1 day before SVX immunization (SVX + αCD8). Data are presented as mean tumor size (mm²) ± SEM from cohorts of 8 mice with *P < 0.05, **P < 0.01 and ***P < 0.001. Experiments have been done twice. (C,D) An additional group of mice for each experiment is shown and represents BALB/c mice (8 mice per group) engrafted with hCT26 (C) or hA20 tumors (D) and depleted of CD8⁺ T cells using anti-CD8 mAbs (100 μg) injected i.p once a week during 3 weeks. Data represent the mean of tumor size (mm²) ± SEM at day 28 (C) or day 32 (D). **P < 0.01 and ***P < 0.001. (E) Intensity of survivin CD8⁺ specific T-cell responses in hCT26 TB mice vaccinated (SVX) or not with SVX (PBS). Evaluation of functional responses was performed 2 weeks after the last vaccination using IFN-γ ELISpot assays on total splenocytes restimulated overnight in vitro with the CD8⁺ T-cell epitope surv85-93. Data are presented as means of IFN-γ spots ± SEM of 16 mice per group from two independent experiments. **P < 0.01. (F) Same mice as in (E). Two weeks after the last immunization, the tumors were harvested, and the percentage of CD8⁺GrB⁺ in TIL was evaluated by flow cytometry. Data are presented as means of percentage of cells ± SEM of 16 mice per group from two independent experiments. ***P < 0.001.