<i>Mtb</i> HN878 induces potent IL-17 responses in infected mice.

<p>B6 mice were either aerosol infected with ∼100 cfu <i>Mtb</i> H37Rv or <i>Mtb</i> HN878. Lungs were homogenized in saline on D30 post-infection and IL-17 protein levels were determined by Luminex (a). IL-17 GFP reporter mice were aerosol infected with ∼100 cfu <i>Mtb</i> H37Rv or <i>Mtb</i> HN878. The frequency (b) and absolute number (c) of lung IL-17-producing cells (GFP⁺) was determined by flow cytometry at D25 post-infection. Representative flow cytometry histograms of lung cell suspensions from uninfected (Un), <i>Mtb</i> H37Rv or <i>Mtb</i> HN878-infected IL-17 GFP reporter mice is shown (d). The number of CD3⁺IL-17⁺ lung cells was determined by flow cytometry (e). The percentage of ESAT-6_1–20-specific, IL-17 (f) and IFN-γ (g) producing cells in the lungs of these mice was determined by ELISpot assay. 1×10⁶ lung CD11c⁺ cells from B6 mice and infected in vitro with <i>Mtb</i> H37Rv or <i>Mtb</i> HN878 (MOI 0.01). Subsequently, naïve B6 total lung cell suspensions were added to the culture, and 6 days later, IL-17 levels were determined in supernatants by ELISA (h). The data points represent the mean (±SD) of values from 3–5 samples. *p≤0.05, **p≤0.005, ***p≤0.0005. ns-not significant.