Type 1 immunity elicited by footpad immunization with NK1R-DCs requires IL-12p70 released by host DCs. (A) Secretion of IFN-γ (analyzed by ELISA) by splenic CD4 T cells from WT or IL-12p35^KO C57BL/6 mice 7 days after footpad immunization (1 dose) with untreated DCs, Ag-DCs, or Ag-NK1R-DCs. (B) Percentage of Ag-specific CTL function (in vivo killing assays) in WT or IL-12p35^KO C57BL/6 mice, 7 days following footpad immunization (1 dose) as described in panel A. (C) Secretion of IFN-γ (analyzed by ELISA) by splenic CD4 T cells isolated from WT mice, 7 days after footpad immunization (1 dose) with WT or IL-12p35^KO untreated DCs, Ag-DCs, or Ag-NK1R-DCs. (D) Assessment of IFN-γ–secreting CD4 T cells (by ELISPOT) from spleens of CD11c-DTR mice, depleted or not of host DCs with DT injection 1 day before immunization, and analyzed 7 days following footpad immunization. (E) Percentage of Ag-specific CTL activity (determined using in vivo killing assays) in CD11c-DTR mice treated or not with DT 1 day before administration of untreated DCs, Ag-DCs, or Ag-NK1R-DCs, analyzed 7 days after vaccination. Means ± 1 SD from 5 mice per group are shown. NS, not significant difference.