CD8+ T Cells in Tuberculosis

This chapter focuses on CD8 T cells, with an emphasis on the major histocompatibility complex (MHC) Ia-restricted T cells in tuberculosis, and also touches upon the unconventional CD8 T cells restricted by β2m-associated nonclassical MHC Ib or MHC I-like molecules. Although the T cells which recognize mycobacterial glycolipids in the context of group I CD1 molecules are not only CD8+ but also double negative and sometimes even CD4+, they are considered in this chapter where appropriate. Importantly, dendritic cells (DC) can capture an antigen at the site of infection and transport it to draining lymph nodes, where T-cell stimulation takes place. The possible functions of CD8 T cells in the control of tuberculosis include cytokine production, macrophage activation, killing of infected cells, and killing of M. tuberculosis. The memory response to M. tuberculosis in the lungs is weak compared to that of some viral infections. A model that has been used to study memory responses is infection of mice followed by antimycobacterial drug treatment beginning 4 weeks after infection. In summary, CD8 T cells that recognize mycobacterial antigens on macrophages or DC are induced following M. tuberculosis. Given the potential for effective immune responses mediated by CD8 T cells, more researchers are using strategies that include the induction of CD8 T cells in vaccine candidates for tuberculosis. The results of these studies may provide important data on the ability of CD8 T cells to contribute to protection against this disease.