Figure 4.

CLEC12A plays a limited role in lung infection by L. pneumophila in mice. (A) WT and Clec12a^−/− C57BL/6 mice were infected with L. pneumophila at a dose of 10⁶ CFU/mouse, and the bacterial loads from their lungs were assessed at 24, 48 and 96 h after infection by plating serial dilutions of homogenized lungs on BYCE agar. (B,C) Infected WT and Clec12a^−/− C57BL/6 mice were monitored for temperature (B) and body weight (C) over the course of the infection experiment. The expression levels of Ifnb1 in homogenized murine lungs 24 h after infection were assessed by qRT-PCR and normalized to the lungs of PBS-treated WT mice (D). (E–G) The levels of IFNγ, TNFα and IL-6 in mouse lungs were measured 24 h after infection. (H) Representative flow cytometric analyses of alveolar macrophages (AMs; CD45⁺, CD11c⁺, CD11b⁻, Siglec-F⁺), inflammatory monocytes (iMonos; CD45⁺, CD11c⁻, CD11b⁺, Ly6C⁺) and polymorphonuclear neutrophils (PMNs; CD45⁺, CD11c⁻, CD11b⁺, Ly6G⁺). Green arrows indicate the gating strategy. (I–N) Percentages and numbers of AMs, iMonos and PMNs in the lungs of WT and Clec12a^−/− mice 24 h after infection. All data represent the means ± SD of 2 independent experiments, with 4 to 5 mice per experiment. Differences were assessed using a two-way ANOVA and the Mann–Whitney U-test. Comparisons with p < 0.05 were considered significant.