CD4 and tuberculosis: In contrast, after restimulation with anti-CD3/CD28, the relative number of polyclonal IL-17A-expressing CD4+ T cells was highest in lung homogenates with approximately 4% in wild type and 3% in IL-6−/− mice already 14 days after Mtb infection, declined until day 42 and increased at day 98 of experimental TB (Figure 1a).