Immune Response to Mycobacterium tuberculosis: A Narrative Review

Abstract

The encounter between Mycobacterium tuberculosis (Mtb) and the host leads to a complex and multifaceted immune response possibly resulting in latent infection, tubercular disease or to the complete clearance of the pathogen. Macrophages and CD4 + T lymphocytes, together with granuloma formation, are traditionally considered the pillars of immune defense against Mtb and their role stands out clearly. However, there is no component of the immune system that does not take part in the response to this pathogen. On the other side, Mtb displays a complex artillery of immune-escaping mechanisms capable of responding in an equally varied manner. In addition, the role of each cellular line has become discussed and uncertain further than ever before. Each defense mechanism is based on a subtle balance that, if altered, can lean to one side to favor Mtb proliferation, resulting in disease progression and on the other to the host tissue damage by the immune system itself. Through a brief and complete overview of the role of each cell type involved in the Mtb response, we aimed to highlight the main literature reviews and the most relevant studies in order to facilitate the approach to such a complex and changeable topic. In conclusion, this narrative mini-review summarizes the various immunologic mechanisms which modulate the individual ability to fight Mtb infection taking in account the major host and pathogen determinants in the susceptibility to tuberculosis.

RNA Sensing of Mycobacterium tuberculosis and Its Impact on TB Vaccination Strategies

“…It has been argued that the very first response to infection with MTB defines its success [124]. Thus, it seems plausible to reexamine PRRs and APCs to find new prophylactic and therapeutic targets.…”

Development of a TB vaccine trial site in Africa and lessons from the Ebola experience.

“…Economic losses, in West Africa and globally, were estimated at USD 18 billion as a result of the 2014-2016 outbreak (23). The annual societal cost alone of TB is USD 19 billion (24).…”

“…shows selected requirements thought to impact the feasibility of accelerated vaccine development. Mycobacterium tuberculosis is considerably more complex, with great capacity to evade host immunity(24). Also, animal models that closely mimic human disease are better for Ebola virus than TB.…”

Absolute eosinophil count correlates with temperature and CD4 count independently of HIV infection among tuberculosis patients

“…Tuberculosis (TB) is the leading cause of mortality from a single infectious agent globally [1]. Host immune responses against Mycobacterium tuberculosis (Mtb) involve a complex interplay of effector functions of airway epithelial cells, macrophages, neutrophils, dendritic cells, natural killer cells, mast cells, CD4+ and CD8+ T lymphocytes [2]. The role of eosinophils in the host's immune response to Mtb is not well characterised in humans.…”