CD28 and tuberculosis: To directly assess the question which cell types produce IL-22 during experimental TB, C57BL/6 mice were infected with a low dose of Mtb for 22 days, and the production of IL-17A, IFNγ and IL-22 in CD90.2+CD4+ cells was analysed by flow cytometry after restimulation of lung cells with anti-CD3/CD28 and intracellular cytokine staining (Figure 2).