ATF3^−/−neutrophil lung recruitment in impaired. (A) BAL fluid from WT mice challenged with increasing amounts of rCXCL1 i.t. were evaluated to determine neutrophil recruitment to the lung after 18 to 24 hours by microscopic evaluation of cytospins. Representative of 2 independent experiments, N = 3 to 5 mice/group. Statistics are 1-way ANOVA. (B) LPS (10 ng) and 50 μg isotype control (white bars) or neutralizing CXCL1 antibody (black bars), were coadministered i.t. to WT mice. Neutrophil content of BALF was determined as in A. Representative of 2 independent experiments; N = 3 to 5 mice/group. Statistics are unpaired 2-tailed Student t test. (C) WT (dotted lines) and ATF3^−/− (black lines) mice were challenged i.t. with 10 ng LPS and neutrophils enumerated as in A. Representative of 8 independent experiments; N = 3 to 7 mice/group. (D) BM chimeras from Figure 2A were challenged and neutrophil recruitment determined as in A. Representative of 3 independent experiments; N = 14 to 16 mice/group. Statistics are unpaired Student 2-tailed t test. Data are mean ± SEM. *P < .05, ***P < .001.