FIG 5.

IFN-λ inhibits phagocytosis of MRSA during superinfection. (A and B) Mice were infected with influenza and 5 days later given Ad-IFN-λ or Ad-GFP as described in the legend of Fig. 1. Twenty-four hours later, mice were challenged with 5 × 10⁷ CFU of FITC-labeled MRSA (A) or FITC-labeled S. pneumoniae (B) and sacrificed 1 day later. The left lobe of the lung was digested to a single-cell suspension and stained for flow cytometry. We report the percentage of FITC⁺ neutrophils as analyzed by flow cytometry (percentage of live CD45⁺ Ly6G⁺ CD11b⁺ cells that were FITC⁺) as well as the percentage of total immune cells in the lung that are neutrophils (percentage of live CD45⁺ cells that were Ly6G⁺ CD11b⁺) (n = 4; two independent experiments). (C) Representative flow cytometry plot showing the gating strategy for determining FITC positivity in neutrophils from mice treated with Ad-GFP or Ad-IFN-λ during influenza/MRSA superinfection. *, P < 0.05; **, P < 0.01. FSC, forward scatter.