Fig 1: IL-3 drives MK maturation in the spleen during sepsis.(A) Expression of Thpo and Il3 in the spleen as assessed by qPCR, 1 day after saline or CS injection. n = 10, n = 10 and n = 7, n = 10 mice, respectively. (B) Blood levels of TPO and IL-3 after saline injection 3 days after CS injection. n = 13, n = 9, n = 10 and n = 10, n = 8, and n = 9 mice, respectively. (C) Surface expression of IL-3Ra (CD123) on MEPs and MKs in the BM (left) and spleen (right). (D and E) Flow cytometric analysis of MKs in the spleen (D) and BM (E), 5 days after CS injection and treatment with anti-HRP or anti–IL-3–neutralizing antibody. n = 9 and n = 7 mice, respectively. Ctrl, control. (F and G) 2PIVM images (F) and analysis (G) of MKs and platelet production (arrows) in the spleen in Pf4-mTmG mice 5 days after CS injection and treatment with anti-HRP or anti–IL-3–neutralizing antibody. n = 4 and n = 5 mice, respectively. Scale bars: 50 µm. (H and I) 2PIVM images (H) and analysis (I) of MKs and platelet production (arrows) in the BM in Pf4-mTmG mice 5 days after CS injection and treatment with daily anti-HRP or anti–IL-3 antibody. Scale bars: 30 µm. n = 7 and n = 5 mice, respectively. Data indicate the mean ± SEM. **P < 0.005 and ***P < 0.0001, by 2-tailed, unpaired Student’s t test.