Autocrine IL-6 and IL-23 induced IL-17 production in neutrophils with MTB H37Rv infection. (a) Il6, Il23 and Il17a mRNA expression in neutrophils infected with MTB H37Rv for indicated time points determined by real-time PCR. All gene quantities were normalized to the expression of the reference gene β-actin. (b) IL-6, IL-23 and IL-17 secretion by neutrophils infected with MTB H37Rv for indicated time points was measured by ELISA. (c) Expression of intracellular IL-17 by neutrophils uninfected or infected with MTB H37Rv for 24 h. (d) Il17a expression in neutrophils infected with MTB H37Rv for 18 h plus no antibody (-) or neutralizing antibody (Ab) to IL-6 or IL-23. (e) WT mice were infected with MTB H37Rv, and then treated with either isotype control mAb or anti-Ly6G mAb for 4 days once a day from the day before the infection. Concentrations of IL-6, IL-23 and IL-17 in serum were quantified. Data shown in (a–c, e) are the mean ± SEM. *P < 0.05. Data are representative of three independent experiments with similar results.