Figure 8.

DCs specifically require type I IFN sensitivity for tumor immunity in vivo. (A) IFNAR1 expression on splenic CD8α⁺ DCs, CD4⁺ DCs, pDCs, LN CD103⁺ DCs, and dermal DCs was measured using flow cytometry in Ifnar1^f/f, Itgax-Cre⁺Ifnar1^f/f, and Ifnar1^−/− mice. (B) Summary of IFNAR1 levels on the indicated cellular subsets in Itgax-Cre⁺Ifnar1^f/f mice compared with Ifnar1^f/f mice (expressed as a percentage of control mean fluorescence intensity [MFI]). Cells were gated as follows: CD8α⁺ DCs (CD8α⁺Dec205⁺CD11c^hi), CD103 DCs (CD8α⁻Dec205⁺CD11c^hiCD103⁺), CD4⁺ DCs (CD8α⁻Dec205⁻CD11c^hiCD4⁺), dermal DCs (CD8α⁻CD11c^hiCD103⁻), pDCs (B220⁺PDCA⁺CD11c^int), B cells (B220⁺), T cells (CD3⁺), NK cells (NK1.1⁺), macrophages (CD11b⁺F4/80⁺), and blood PMNs (CD11b⁺Gr1⁺). IFNAR1 expression was measured using the MAR1-5A3 mAb. Data represent three to five mice from at least three independent experiments. (**, P < 0.01). (C) Splenocytes from Itgax-Cre⁺Ifnar1^f/f mice were untreated (gray) or stimulated for 15 min with 10 ng/ml IFN-α_v4 (black), and pSTAT1 accumulation in CD8α⁺ and CD4⁺ DCs was measured by flow cytometry. Histograms show a representative experiment, and the bar graph summarizes results from four independent experiments (**, P < 0.01). (B and C) Error bars represent SEM. (D) C57BL/6 WT, Ifnar1^−/−, Ifnar1^f/f, and Itgax-Cre⁺Ifnar1^f/f mice were injected s.c. with 10⁶ 1969 unedited sarcoma cells. Mean tumor diameter ± SEM from a representative experiment is shown, and the bar graph shows a summary of the percentage of tumor-positive mice per group from three independent experiments with indicated groups sizes (P < 0.001 [WT vs. Ifnar1^−/−] and P < 0.001 [Ifnar1^f/f vs. Itgax-Cre⁺Ifnar1^f/f]) using the Student’s t test at day 23. Comparisons of Ifnar1^−/− versus Itgax-Cre⁺Ifnar1^f/f or WT versus Ifnar1^f/f were not significantly different.