Fig. 1

Vaccine-induced immunity to mycobacteria. Dendritic cells (DCs) are activated by vaccine components, such as adjuvants engaging pattern recognition receptors (PRRs), which leads to the presentation of peptide fragments to CD8⁺ and CD4⁺ T-cells. Both Th1 and Th17 CD4⁺ T-cell subsets are associated with protective responses in animal models of M. tuberculosis infection, in particular through the stimulation of infected host cells such as macrophages (MAC) to eliminate ingested bacteria. Cytokines (e.g. IL-2) secreted by Th1 CD4⁺ T-cells promote the maintenance of memory T-cell populations (Tmem). Although B cells may be stimulated to produce antibody upon vaccination, they appear to have little role in protection against mycobacteria and are not typically a target of rationally designed vaccines