Characterization of CD70tg DCs. CD27^−/− (control) or CD70tg;CD27^−/− (CD70tg) donor mice were injected subcutaneously with B16 melanoma cells that secrete Flt3L, and analysis was performed 2 weeks later. (A) Mean numbers + SEM of CD11c⁺ cells in spleens of Flt3L-treated control and CD70tg mice and untreated WT mice (n = 5). (B) DC subset distribution. DCs were isolated from spleen by density gradient centrifugation; stained with directly conjugated antibodies to CD11c, CD45R/B220, CD4, CD8α, CD70, and CD40; and analyzed by flow cytometry. Gating strategy to identify pDC and cDC subsets and their percentage are indicated. (C) Expression of CD70 at the cell surface of pDCs and cDCs isolated from untreated WT and Flt3L-treated control and CD70tg mice, as determined by flow cytometry on gated populations as indicated above. (D) CD40 expression on unstimulated or LPS-stimulated DCs from untreated WT mice and on DCs from Flt3L-treated control and CD70tg mice. Data are representative of 2 independent experiments.