Figure 1.

Tuberculosis pathogenesis and disease progression. Mycobacterium tuberculosis infection initiates with inhalation of droplets that carry bacteria and their uptake by alveolar macrophages. Innate immune responses characterize the initial phase of infection, with recruitment of inflammatory cells in the lung. Bacterial dissemination to the draining lymph node leads to T cell priming and expansion of antigen-specific T cells. Recruitment of activated macrophages, neutrophils, T cells, and B cells in the lung leads to granuloma formation, which contains M. tuberculosis in a latent status. However, in about 10% of infected individuals, M. tuberculosis escapes immune control and granulomas are disrupted, with release of infectious bacteria.