ERα signaling in pDCs is required to mediate the enhancing effect of E₂ on the TLR-mediated production of IFN-α. (A-D) Ovariectomized CD11c-ERα^KO female or ERα^fl/fl control littermates on a B6 background were treated or not with E₂ as in Figure 5. (A) Absolute numbers of bone marrow pDCs from individual mice. P value was determined using the Mann-Whitney U test. pDCs were FACS-purified from pooled bone marrow cells (3-5 mice per group) and stimulated with the indicated amounts of the TLR-9 ligand CpG-2216. Culture supernatants were collected after 24 hours of stimulation, and IFN-α (B), TNF-α (C), and IL-12p40 (D) concentrations were measured by ELISA. Data are representative of 2 independent experiments. (E-G) Bone marrow pDCs were purified from intact female CD11c-ERα^KO or ERα^fl/fl control mice, and the production of IFN-α (E) and TNF-α (F) on TLR-9 stimulation was analyzed by ELISA. (G) Intact CD11c-ERα^KO (n = 5) or ERα^fl/fl (n = 4) female mice were injected intravenously with 2 μg of CpG-2216, and their serum IFNα concentration was then assessed by ELISA at the indicated time points.