The systemic neutrophil response following P aeruginosa infection is impaired in G-CSFR^−/− mice. (A) The serum concentration of G-CSF in wild-type mice at the indicated times following P aeruginosa infection was measured by ELISA. (B) The absolute neutrophil count in the blood was measured in wild-type and G-CSFR^−/− mice (n = 8-26, each time point). (C) The number of mature neutrophils per femur was measured in wild-type and G-CSFR^−/− mice (n = 4-17, each time point). (D) The percentage of the total body pool of mature neutrophils present in the blood was estimated as described in “Materials and methods” (n = 4-17, each time point). All data represent the mean ± SEM. ‡P < .05 compared with untreated mice of the same genotype. *P < .05 compared with G-CSFR^−/− mice.