CD4 and tuberculosis: Despite reports that IL-22 deficiency or neutralization does not alter the outcome of M. tuberculosis infection in mice [32, 65], studies in patients with tuberculosis have shown the presence of IL-22-producing CD4+ T cells: Scriba et al. demonstrated that a substantial proportion of mycobacteria-specific Th cells from healthy M. tuberculosis-exposed individuals produce IL-22 and are distinct from Th17 and Th1 cells, implicating IL-22 as an important cytokine axis in human antimycobacterial immunity [20].