Neutrophilia in c-FLIP^f/f LysM-Cre mice is G-CSF–dependent. (A) Expression of G-CSF, IL-1β, IL-17, and MIP-1α in serum of 4-week-old c-FLIP^f/f (black bars) or c-FLIP^f/f LysM-Cre (white bars) mice as determined by multiplex cytokine assay. Data presented were obtained in a single experiment, and are representative of 2 independent experiments. n = 3; NS, not significant; **P < .01; ***P < .001. (B-D) In vivo inhibition of G-CSF and IL-1 signaling. (B) Absolute numbers of circulating neutrophils and monocytes in c-FLIP^f/f (black bars) or c-FLIP^f/f LysM-Cre (white bars) mice before and after combination treatment with anti-G-CSF antibody and IL-1Ra. (C-D) Absolute numbers of bone marrow B cells, neutrophils, and progenitor cells (C), or splenic neutrophils, inflammatory monocytes, and progenitor cells (D) in c-FLIP^f/f (black bars) or c-FLIP^f/f LysM-Cre (white bars) mice after 15 days of combination treatment with anti-G-CSF antibody and IL-1Ra. Data were obtained in 2 independent experiments. (n = 4-7; NS, not significant; *P < .05. (E-F) Frequency of neutrophils in peripheral blood of c-FLIP^f/f (black bars) or c-FLIP^f/f LysM-Cre (white bars) mice treated daily beginning at 4 weeks of age with neutralizing anti–G-CSF antibody (E) or IL-1Ra (F). Data were obtained in a single experiment (n = 5 (E) or n = 3-5 (F); NS, not significant; *P < .05; ***P < .001). (G) Body weight of c-FLIP^f/f (black bars) or c-FLIP^f/f LysM-Cre (white bars) mice treated daily beginning at 4 weeks of age with IL-1Ra. Data were obtained in a single experiment. n = 3-5; NS, not significant; *P < .05; **P < .01; ***P < .001. Error bars represent standard deviations.