Chemotactic responses and requirement for CD11b in exaggerated neutrophil recruitment of siglec-E–deficient mice exposed to LPS. (A) CXCL1 and CXCL2 levels were measured in serum, bronchoalveolar lavage (BAL) fluid, and lung tissue homogenate by enzyme-linked immunosorbent assay from WT mice and siglec-E^R126D mice 30 minutes after LPS aerosol. Data are expressed as means ± SEM; n = 4-5 per group. (B) A 1:1 mix of WT and siglec-E^−/− mice bone marrow cells were placed into transwell chemotaxis chambers, and the number of cells migrating was determined by flow cytometry. Data are expressed as means ± SEM of triplicate wells. (C) Mice were injected intravenously with 100 µg anti-CD11b antibody (5C6 clone 1) or rat IgG immediately preceding exposure to aerosolized LPS and cellular recruitment analyzed at 3 hours in BAL or in lung tissue digests (Lung). Data are expressed as means ± SEM; n = 4-9 per group from 2 independent experiments; and *P < .05, Mann-Whitney U test compared with WT mice.