After <i>Mtb</i> infection, IL-22 expression is IL-23 dependent.

<p>Experimental mice were infected with <i>Mtb</i> via the aerosol route. (<b>A</b>) Before and at different time points of infection with approx. 100 CFU <i>Mtb</i>, gene expression of <i>Il22</i>, <i>Il12b</i>, <i>Il17a</i>, <i>Il17f</i>, and <i>Il23p19</i> was quantified by real time RT-PCR in lung homogenates of C57BL/6 mice based on the expression of <i>Hprt</i>. Data represent mean ± SD of 5 mice per group. (<b>B</b>) Twenty days after infection with approx. 1000 CFU <i>Mtb</i> of C57BL/6 (black symbols) and IL-23p19^−/− (white symbols) mice, gene expression of <i>Il22</i> was quantified by real time RT-PCR in lung homogenates based on the expression of <i>Hprt</i>. Data represent mean ± SD for of 5 mice per group. Statistical analysis was performed using the Student’s <i>t</i> test defining differences between C57BL/6 and IL-23p19^−/− mice as significant (***, p<0.001).