CD8α⁺ DCs are critical for antitumor CD8⁺ T cell priming. Wild-type and Batf3^−/− mice were inoculated s.c. with 10⁶ B16.SIY cells. 6 d later, splenocytes were harvested and restimulated for 16 h in the presence of culture medium or soluble SIY peptide (A). The frequency of tumor-specific IFN-γ–producing cells was assessed by ELISPOT. ***, P < 0.0001 versus WT. (B) the frequency of SIY-specific CD8⁺ T cells was assessed by FACS using specific anti–K^b-SIY tetramers, cells were gated on the CD8⁺CD4⁻B220⁻ population. ***, P < 0.001 versus WT. (C) IFN-β mRNA expression was assessed by real-time RT-PCR analysis in total lymph nodes. The results are expressed as 2^−ΔCt using 18s as endogenous control. Results are shown as mean ± SEM (n = 5) and are representative of at least two experiments.