This cell preparation yielded >95%

of PMNs (by Ly-6G (1A8) FACS analysis) with a more than 99% viability (by trypan blue exclusion, Supporting Information Fig. 5). Migration assays were performed using a modified 48-well Boyden microchemotaxis chamber (Neuroprobe, Bethesda, MD) in which an 8-μm pore-size cellulose nitrate filter separated the upper and the lower chamber [43]. For chemotaxis, 50 μL of a cell suspension (1 × 106 cells/mL) was put into the upper compartment of the chemotaxis chamber, and cells were allowed to migrate for 30 min (neutrophils) toward soluble chemoattractants in the lower wells. Neutrophils were prestimulated with different concentrations of rhIL-8 (R&D Systems, Vienna, Austria), rmKC (R&D Systems), rmLcn2 (R&D Systems), rhLcn2 mAb (R&D Systems). For blocking, experiments cells were preincubated with either U0126 (100 nM), BI 2536 in vivo U0124

(100 nM), wortmannin (5 nM), or calphostin (50 nM; all inhibitors used are from Calbiochem, Nottingham, UK). After the migration period, the nitrocellulose filters were dehydrated, fixed, and stained with H&E. Migration depth of the cells into the filters was quantified by microscopy C646 by an experienced analyzer blinded to the study design, measuring the distance (μm) from the surface of the filter to the leading front of cells. Data are expressed as a chemotaxis index, which is the ratio between the distance of directed and undirected migration of cells into the nitrocellulose filters. WT Suplatast tosilate and Lcn2-deficient littermates were injected i.p. with 1 mL of 2.4% thioglycolate or 1 mL of PBS at time 0. After 1, 2, or 4 h, mice were sacrificed and injected i.p. with 3 mL of ice-cold PBS (without Ca2+ and Mg2+, with 50 U/mL heparin), their abdomen were massaged and total lavage fluid was withdrawn. Total cell numbers were determined

by VetABC (veterinary animal blood cell counter). KC and CXCL10 were measured in lavage fluid (R&D Systems). Salmonella enterica serovar Typhimurium strain ATCC 14028 (300 CFU in 50 μL of saline) were intradermally injected into WT (Lcn2+/+) and KO (Lcn2−/−) mice. After 24 and 48 h, mice were sacrificed and the skin was excised at each injection site, fixed in formalin and stained with H&E for histopathological analysis. For immune fluorescence analysis, formalin-fixed skin tissue was embedded in paraffin and cut in 4-μm sections. For detection of S. typhimurium within the skin lesion, we dehydrated paraffin sections and performed Ag retrieval by using a commercially available Ag-unmasking citric-acid buffer (Vector Laboratories, Burlingame, CA, USA). For the staining procedure, we used the anti-CSA-1 FITC-labeled Ab (KPL, WA, USA). In order to mobilize PMNs from BM, we injected LPS from E. coli 055:B5 (2 μg/g body weight) dissolved in a volume of 200 μL of NaCl (0.9%) i.v. into mice. Blood was drawn by retroorbital blood puncture.for leukocyte quantification and FACS analysis.