FIGURE 5.

StII coencapsulated into DPPC:Cho Lp with the Ag induces remarkable antitumor prophylactic immunity that decreases upon depletion of CD8⁺ T lymphocytes. C57BL/6 mice were immunized i.m. twice with Lp/OVA (50 µg OVA) or Lp/OVA/StII (50 µg OVA and 6.25 µg StII) on days 0 and 12. Mice were challenged 7 d later with 3 × 10⁵ cells E.G7-OVA tumor cells. A group of mice received PBS as control. Time courses of tV increase (mean ± SEM) (A), tumor grafting (B), and survival curves (C) in experimental groups after tumor challenge. Data are representatives of three independent experiments, each including 7–10 mice per group. Different letters indicate statistical differences among groups based on the Dunnett T3 test (A) and the log-rank test (B and C). The p values are specified in the Results. In another similar antitumoral assay, but immunizing s.c. only with Lp/OVA/StII (OVA 50 µg), mice were depleted of CD8⁺ T cells by i.p. injection of anti-CD8 mAb (1 mg/mice) 1 d before tumor challenge or they received PBS instead of anti-CD8 (nondepleted group). Time courses of tV increase (mean ± SEM) (D), tumor grafting (E), and survival curves (F) of experimental groups. Statistically significant differences were estimated by the Mann–Whitney U test between the mice groups depleted or not of CD8⁺ T lymphocytes (D) and the log-rank test (E and F). Different letters indicate statistical differences among groups (p values are specified in the Results). Two experiments were performed with similar results. **p < 0.01.