These RXDX-106 datasheet cells produce T-helper type 1 (Th-1) cytokines [interferon (IFN)-γ, interleukin (IL)-2, IL-12] important for the activation of antimycobacterial activities of macrophages (Sable et al., 2007). However, some unconventional T cells (CD4CD8 αβ T-cells, γδ cells, NK 1.1) have also been implicated in protective immunity to tuberculosis through the recognition of nonprotein mycobacterial antigens including glycolipids (mycolic acids, phosphatidylinositol mannosides, lipoarabinomannan, etc.) and their presentation to a variety of CD1-restricted lymphocytes. These cells also activate antigen-presenting cells (APCs), boost the expression of major histocompatibility complexes (MHCs) and

costimulatory molecules

and amplify IL-12, SB525334 IL-18 and IFN-γ production (Doherty & Andersen, 2005). Recently, the importance of CD8+ cytotoxic T-lymphocyte (CTL) responses to the generation of an effective vaccine against tuberculosis has also been recognized. Accumulating evidence indicates that the MHC-I pathway is critical to achieve protection (Orme, 2006). Studies with endogenous proteins, such as heat shock protein 65 (HSP65), have shown the superiority of these antigens to stimulate CTLs, which are able to either kill infected macrophages unable to eliminate the bacilli or kill the mycobacteria in the extracellular space directly (Lima et al., 2004). On the other hand, the role of Th-2 cytokines, such as IL-4, IL-5, IL-10 and IL-13, in protective immunity against selleck chemical Mtb remains unclear. It has been suggested that generation of a Th-2 response is associated with a greater risk of progression from Mtb infection to active disease by seriously undermining the efficacy of a Th-1 response to mycobacterial antigens (Doherty & Andersen, 2005). Some authors have also observed a relationship between the presence

of concomitant parasite infections and exposure to environmental mycobacteria, with a systemic bias towards Th-2 responses that reduces the efficacy of BCG (Rook et al., 2001). In this context, effective tuberculosis vaccine design is based on generating the cellular responses required to kill the bacteria and prevent establishment of infection (against infection and pulmonary disease) or to avoid reactivation or progression toward clinical tuberculosis in the case of latent patients. In the first case, the general strategy involves a prophylactic vaccine able to induce protective immunity, measured in terms of lymphocyte subsets expanded after immunization. In the second case, the strategy focuses on utilizing a postexposure vaccine to eliminate or contain latent tuberculosis and prevent reactivation (Sadoff & Hone, 2005; Sable et al., 2007). Concerns regarding the use of postexposure vaccines and their adverse influences result from the fact that the infected lung has already undergone inflammation, tissue damage and remodelling responses (Orme, 2006).