Reduced numbers of all DC types in IL-7^−/− mice and IL-7Rα^−/− chimeras. (A) Immunofluorescence staining of adult pLNs and spleens of WT and IL-7^−/− mice. Anti-B220 and anti-CD3 stainings outline the B and T zones, respectively. Anti-laminin stainings visualize vessels, stromal cells, LN capsule, and splenic marginal sinus. Anti-CD11c stainings on consecutive sections indicate the localization and density of DCs. Bar represents 100 μm. Data are representative of 3 independent experiments. (B) Cells isolated from the pLN or spleen were stained and the indicated DC subtypes, T cells, B cells, and granulocytes analyzed by flow cytometry (gating as in Figure 3). Mean cell numbers in WT mice were defined as 100%. Relative cell numbers (± SD) per LN or spleen are shown for WT versus IL-7^−/− mice. Data are representative of a total of 3 to 9 mice per group. (C) Irradiated CD45.1⁺ CD45.2⁺ B6 mice were reconstituted with either CD45.2⁺ IL-7Ra^−/− (n = 3) or CD45.1⁺ WT BM (n = 2) and analyzed after 16 weeks as described in panel B except for pDCs, which were identified as small CD11c^int GR-1⁺ B220⁺ CD11b⁻ cells. Only numbers of donor-derived cells are shown. *P < .05; **P < .01; ***P < .001.