The peripheral pDC defect in Cxcr4^+/1013 mice results from impaired CXCR4-dependent pDC egress from BM. (A) Representative dot plots showing the gating strategy to identify pre-cDCs (CD11c^loCD317⁻ gated on live CD4⁻CD8⁻B220⁻CD11b⁺MHC2^−/int cells) and pDCs (CD11c^loCD317⁺ among live B220⁺ cells) in the BM of +/1013 and WT mice. (B) Pre-cDC and pDC frequencies (top bar graphs) and numbers (bottom bar graphs) in the BM of +/1013 and WT mice (means ± SEM, n = 7-8 mice from 4 experiments for pre-cDC, n = 17 mice/group from 6 experiments for pDC frequency, n = 10-11 mice from 4 experiments for pDC number). (C) Numbers of blood pDCs and Gr1⁺ cells assessed 2 hours after intraperitoneal injection of AMD3100 or phosphate-buffered saline (mean ± SEM, n = 3 mice/group, 1 representative experiment of 2). (D-F) Parabiosis experiments were performed with CD45.1 Cxcr4^+/+ (WT, left parabiont) and CD45.2 Cxcr4^+/1013 (+/1013, right parabiont) mice. Blood, spleen, and BM were analyzed 8 weeks later. (D, right) Representative dot plots showing CD45.1 and CD45.2 expression in blood pDCs from WT and +/1013 parabionts. (E) Nonhost chimerism in the blood, spleen, and BM from each parabiont. pDC was defined as live CD3⁻Ly6G⁻CD11b⁻CD115⁻CD11c^loCD317⁺Ly6C⁺B220⁺ cells and Ly6C^lo monocytes as live CD3⁻B220⁻Ly6G⁻CD115⁺CD11b⁺CD317⁻Ly6C^lo cells. (F) Spleen/blood ratios of WT and Cxcr4^+/1013 pDCs and Ly6C^lo monocytes calculated for the spleen of WT (white background) and Cxcr4^+/1013 (gray background) parabionts (mean ± SEM, n = 5 pairs of mice). Mice had a C57BL/6J genetic background. Statistical analysis was performed using the paired t test. *P < .05, **P < .01, ****P < .001.