Early clearance of Mycobacterium tuberculosis: a new frontier in prevention

AJ Verrall, M G. Netea, B Alisjahbana, PC Hill… - …, 2014 - Wiley Online Library
AJ Verrall, M G. Netea, B Alisjahbana, PC Hill, R van Crevel
Immunology, 2014Wiley Online Library
Early clearance (EC) is the successful eradication of inhaled M ycobacterium tuberculosis
before an adaptive immune response develops. Evidence for EC comes from case contact
studies that consistently show that a proportion of heavily exposed individuals do not
develop M. tuberculosis infection. Further support for the existence of this phenotype comes
from genetic loci associated with tuberculin reactivity. In this review we discuss aspects of
the innate response that may underpin EC and hypotheses that can be tested through field …
Summary
Early clearance (EC) is the successful eradication of inhaled Mycobacterium tuberculosis before an adaptive immune response develops. Evidence for EC comes from case contact studies that consistently show that a proportion of heavily exposed individuals do not develop M. tuberculosis infection. Further support for the existence of this phenotype comes from genetic loci associated with tuberculin reactivity. In this review we discuss aspects of the innate response that may underpin EC and hypotheses that can be tested through field laboratory link studies in M. tuberculosis case contacts. Specifically, we consider mechanisms whereby alveolar macrophages recognize and kill intracellular M. tuberculosis, and how other cell types, such as neutrophils, natural killer T cells, mucosa‐associated invariant T cells and γδ T cells may assist. How EC may be impaired by HIV infection or vitamin D deficiency is also explored. As EC is a form of protective immunity, further study may advance the development of vaccines and immunotherapies to prevent M. tuberculosis infection.
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