NKT cells, NK cells, and CD8 T cells are required for therapeutic efficacy of the vaccine. WT or genetic knockout mice were challenged with 1 × 10⁵ Eμ-myc 299 tumor cells and treated on day 5 with irradiated, α-GalCer–loaded tumor cells, or left untreated. (A) Eμ-myc tumor burden in blood 19 days after tumor inoculation, in untreated or vaccine-treated WT, NKT cell–deficient Jα18^KO, and gamma/δ T cell–deficient TCRδ^KO mice. As indicated, some WT mice received mAb-based depletion of NK cells (anti-aGM1), CD8 T cells (anti-CD8β), CD4 T cells (anti-CD4), or isotype control mAb (cIg). ***P < .0001 (unpaired t test). ns indicates not significant. (B) Percentages of NKT cells (left), NK cells (middle), and CD8 T cells (right) in blood at the indicated time points before and after vaccination in Eμ-myc tumor-bearing and non–tumor-bearing (naive) WT mice. Data are mean ± SEM; n = 5. ***P < .0001 (unpaired t test). **P < .003 (unpaired t test). *P < .03 (unpaired t test). (C) The percentage of NKT cells (left) and NK cells (right) in blood of untreated and treated WT and Jα18^KO mice 12 days after tumor inoculation. Dotted line indicates baseline percentage from an age- and sex-matched non–tumor-bearing mouse. ***P < .001 (unpaired t test). **P < .01 (unpaired t test). *P < .05 (unpaired t test). ns indicates not significant. (A-C) Data are representative of 2 independent experiments.