Granulysin-dependent killing of intracellular and extracellular Mycobacterium tuberculosis by V gamma 9/V delta 2 T lymphocytes

Contribution of V gamma9/V delta2 T lymphocytes to immune protection against Mycobacterium tuberculosis is still a matter of debate. It was reported earlier that V gamma9/V delta2 T lymphocytes kill macrophages harboring live M. tuberculosis through a granule-dependent mechanism that results in killing of intracellular bacilli. This study found that V gamma9/V delta2 T lymphocytes reduce the viability of both extracellular and intracellular M. tuberculosis. Granulysin and perforin, both detected in V gamma9/V delta2 T lymphocytes, play a major role, which indicates that V gamma9/V deltaT lymphocytes directly contribute to a protective host response against M. tuberculosis infection.