TLR7-driven expansion of CD8⁺ T cells is codependent on Type I IFN and IL-12. (A) B6 and IFN-αβR^−/− mice were either untreated or injected with blocking anti–IL-12p40 mAb (C17.8) at both 24 and 2 hours before immunization with 10 μg of the OVA-TLR7a conjugate. (B) B6 mice with or without IL-12 blockade and IFN-αβR^−/− mice were immunized with 10 μg of the OVA-TLR7a conjugate in the footpad. A boost injection of the conjugate was given using the same dose at 30 days post the primary injection. Blood was obtained from the tail vein on (A) day 7 post primary and (B) day 5 post boost injections and stained for OVA-specific CD8⁺ T cells using peptide loaded H-2Kb tetramers. The data shown are representative of 3 independent experiments. The shown dot plots are representative of 3 mice per mouse group in each experiment. Graphed values of the frequency of OVA-specific CD8⁺ T cells are expressed as the mean ± SEM. Statistical analyses (*) were performed as described in “Statistical analyses.”