IL-1α and IL-1β control bacterial burden and neutrophil recruitment in vivo.

(A) 8–12 week old B6 or Il1r1^−/− mice were infected with 1×10⁶ ΔflaA L. pneumophila intranasally (IN). Lungs were plated to quantify CFU per gram. Graph shows the mean ± SEM of three or four infected mice per group. Dashed line represents the limit of detection. (B and C) B6 or Il1r1^−/− mice were infected with 1×10⁶ ΔflaA Lp IN. 24 hours post-infection, bronchoalveolar lavage fluid (BALF) was collected and the percentage of neutrophils in the BALF was quantified by flow cytometry. Percentages are reported as the frequency of live cells in the BALF. (B) Representative flow cytometry plots showing the percentage of Gr-1⁺Ly6G⁺ neutrophils. (C) Graph showing the percentage of neutrophils. Each point represents an individual mouse and lines indicate the mean of 4 mice per group. (D, E, and F) B6 mice were injected intraperitoneally (IP) with either PBS, 100 µg isotype control antibody (iso), 100 µg anti-IL-1α antibody, 100 µg anti-IL-1β antibody, or 100 µg each of anti-IL-1α and anti-IL-1β (anti-IL-1α/β) 16 hours before infection. The mice were then intranasally infected with either 1×10⁶ ΔflaA Lp or mock infected with PBS. (D and E) 24 hours post-infection, BALF was collected and flow cytometry was performed to quantify the percentage of neutrophils. (D) Representative flow cytometry plots showing the percentage of Gr-1⁺Ly6G⁺ neutrophils. (E) Graph showing the percentage of neutrophils. Each point represents an individual mouse, lines indicate the mean of 8 mice per group, and error bars represent SEM. Shown are the pooled results of two independent experiments. (F) 72 hours post-infection, the lungs were plated to quantify CFU per gram. Each point represents an individual mouse. Line indicates the mean of 4 infected mice per group with error bars representing SEM. *** is p<0.001 by one-way ANOVA with Tukey post-test or unpaired t-test (C). **is p<0.01 and *is p<0.05 by unpaired t-test. NS is not significant.