Administration of lentivirally engineered 32Dp210 vaccines in 32Dp210 leukemia-bearing mice confers greater progression-free and overall survival. (A) Overall survival of mice with 32Dp210 leukemia is greatest after serial vaccination with 32Dp210-IL-15/IL-15Rα/CD80: mice were inoculated with 1 × 10⁴ 32Dp210 leukemia cells, and vaccination was initiated 3 days later (depicted in the schema above the graph). Experimental groups included mice inoculated with tumor that received no further treatment (no vaccine, filled gray circles, n = 15) and mice vaccinated with irradiated parental 32Dp210 cells (open red circles, n = 15), 32Dp210-IL-15/IL-15Rα (filled blue squares, n = 15), 32Dp210-CD80 (open green squares, n = 15), or 32Dp210-IL-15/IL-15Rα/CD80 vaccines (filled purple triangles, n = 25). Percent survival is depicted on the y-axis, and duration of survival (days), beginning on day 0 with tumor inoculation, is shown on the x-axis. Data represent the results of 3 independent experiments. (B) In vivo, antibody-mediated depletion of CD8⁺ cells abrogates 32Dp210-IL-15/IL-15Rα/CD80 vaccine effects on overall survival in leukemic mice. After tumor inoculation on day 0, mice underwent 3 weekly vaccinations with 32Dp210-IL-15/IL-15Rα/CD80. Filled purple triangles depict vaccination without antibody depletion. Filled gray circles depict unvaccinated control mice inoculated with 32Dp210 leukemia. Antibody-mediated in vivo depletion of CD8⁺ cells (filled red diamonds, n = 10), CD4⁺ cells (open blue squares, n = 5), and asialo GM1⁺ cells (filled green squares, n = 10) are shown according to the schema at the top of the figure. Percent survival is depicted on the y-axis, and duration of survival (days) on the x-axis.