Lcn2 is required for neutrophil recruitment to the lung during TB.

<p>WT and Lcn2KO were infected with low dose aerosolized <i>M.tuberculosis</i> infection as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050052#pone-0050052-g002" target="_blank">Figure 2</a>. Formalin-fixed paraffin-embedded lung sections from infected WT and Lcn2KO mice were stained for neutrophils (Gr1-red) by immunofluorescence. The number of neutrophils per 20X field was estimated at D20 and D50 (a) and a representative image is shown at 200X magnification (b). Lung cells were isolated from WT and Lcn2KO <i>M.tuberculosis</i>-infected lungs at D50 post infection and the total number of neutrophils (Gr1⁺CD11b⁺) determined by surface staining and flow cytometry (c). Alveolar macrophages isolated from WT mice were exposed to <i>M.tuberculosis</i> (100 µg/ml) alone, Lcn2 alone (10 µg/ml), or both Lcn2 (10 µg/ml) and <i>M.tuberculosis</i> (100 µg/ml) and levels of G-CSF (d), KC (e) were measured in culture supernatants after 48 hours. Alveolar macrophages were isolated from WT or Lcn2KO mice were exposed to <i>M.tuberculosis</i> (100 µg/ml) and exogenous Lcn2 (10 µg/ml) and the levels of G-CSF (f) and KC (g) determined in culture supernatant after 48 hours. The data points represent the mean and SD for 3–4 samples for each time point and one experiment representative of two shown._*, <i>p</i> ≤0.05._**, <i>p</i> ≤0.005._***, <i>p</i> ≤0.0005.