CD8(+) CTL from lungs of Mycobacterium tuberculosis-infected mice express perforin in vivo and Lyse infected macrophages

CD8(+) T lymphocytes have been implicated in the protective immune response against human and murine tuberculosis. However, the functional role that t his cell subset plays during the resolution of infection remains controvers ial. In this study, we demonstrate the presence of Mycobacterium tuberculos is-specific CD8+ CTL in the lungs and lung-draining lymph nodes of mice inf ected with dl. tuberculosis via the aerosol or i.v. route. These cells expr essed perforin in vivo and specifically recognized and lysed M. tuberculosi s-infected macrophages in a perforin-dependent manner after a short period of in vitro restimulation. The efficiency of lysis of infected macrophages was dependent upon the time allowed for interaction between macrophage and M, tuberculosis bacilli. Recognition of infected targets by CD8(+) CTL was beta(2)-microglobulin and MHC class I dependent and was not CD1d restricted . The presented data indicate that CD8(+) T cells contribute to the protect ive immune response during M. tuberculosis infection by exerting cytotoxic function and lysing infected macrophages.