(A) Total leukocytes obtained from enzymatically digested lung. (B, C, and D) Total leukocytes from lung homogenates were prepared for cytospin and counted manually following differential staining. (E and F) WT or CCR2−/− mice were infected for 3 or 5 days with H1N1. Total RNA was extracted and analyzed for expression of the indicated transcript. (G) Lung homogenates were prepared from WT or CCR2−/− mice infected for 3 or 5 days with H1N1 alone and the amount of CXCL1 protein was determined by ELISA. (H) WT or CCR2−/− mice were infected with the indicated pathogen and treated with αGR1 antibody to deplete neutrophils, lung bacterial burden was determined by serial dilution of lung homogenate. Statistical significance was determined by ANOVA, or Kruskal Wallis non-parametric test in panel H. * p < 0.05, ** p < 0.01 (n = 4 – 9 mice per group).