Figure 3.

Model of how cell death is involved in the different stages of M. tuberculosis host infection. In the early stages of infection, killing of macrophages by apoptosis would allow M. tuberculosis to spread cell-to-cell in the lung in the absence of inflammatory mediators associated with necrotic release of intracellular content. This would permit bacteria to replicate in the preferred intracellular environment prior to establishment of an effective adaptive immune response. In the latest stages of infection, when bacterial burden is high, M. tuberculosis would induce necrosis on infected cells leading to mycobacterial release to the extracellular medium. As a consequence, granuloma is disrupted allowing aerosol transmission to new hosts.