Views of immunology: Effector T cells

For many intracellular bacteria, both adaptively acquired and innately encoded effector T cells play a central role in the control, and in some cases, clearance of these pathogens. Through the rapid identification of those cells harboring intracellular bacteria, effector T cells have the capacity to both directly control the infection and shape the immune response to the pathogen. Here, we review the mechanisms by which effector T cells control intracellular infection and emphasize the means by which they recognize their targets. As will become evident, the diversity of both redundant and non-redundant effector mechanisms in conjunction with broad recognition of both protein and non-protein antigens allows for the identification of a broad array of bacterial pathogens and lessens the likelihood of immune evasion.