001). The IFN-γ concentrations in newly diagnosed and relapsed patients were not significantly different from those of patients with chronic TB. However, in vitro stimulation of peripheral blood mononuclear cells (PBMCs) from patients with newly diagnosed, relapsed and chronic TB

with purified protein derivative (PPD) or heat killed M. tuberculosis (H37Ra) enhanced production of granulysin by PBMCs. In vitro, stimulation of PBMCs of newly diagnosed TB patients with PPD produced Selleck IBET762 greater amounts of IFN-γ than did controls, while those stimulated with H37Ra did not. The results demonstrate that patients with active pulmonary TB have low circulating granulysin but high IFN-γ concentrations, suggesting possible roles in host defense against M. tuberculosis for these agents. Tuberculosis is a major

health problem worldwide, with one third of the world population being infected and approximately 1.1–1.7 million deaths annually (1). Most individuals infected with Mtb are asymptomatic. However, 5–10% will progress to active TB during their lifetime, the remainder being resistant to active TB, but remaining infected. Relapse of TB, which is defined as an episode of infection occurring after a previous episode has been treated and considered cured, is possibly due to endogenous reactivation when it occurs in geographical areas with a low incidence of TB infection (2). However, generally the Afatinib supplier risk of relapse depends on the intensity of exposure to Mtb. Other factors that directly affect the clinical course of TB are host factors, including age, immune status, genetic factors and coinfection with HIV, and bacterial factors, including degree tuclazepam of exposure, virulence of strain, MDR and XDR. Protective immunity against Mtb infection involves activated macrophages, antigen-specific T cells and type-1 cytokines such as IL-12, IFN-γ and TNF (3, 4). Inherited defects of the IL-12/IFN-γ pathway appear to result in a variety of changes in mycobacterial susceptibility. People

with genetic deficiencies in the type-1 cytokine (IL-12/IL-23/IFN-γ) axis, and those with neutralizing autoantibody against IFN-γ, have been found to be highly susceptible to mycobacterial infections including TB (5–8). In active pulmonary TB, these effectors of the immune response are activated, as evidenced by observation of high circulating IFN-γ concentrations that decrease significantly following two months of therapy (9, 10). Granulysin can kill extracellular Mtb directly, or intracellular bacteria in the presence of perforin (11), expression of granulysin in CD8+T cells being induced upon activation. It has recently been reported that granulysin is strongly associated with diverse activities of NK cells and CTLs in physiological and pathological settings, and might be a useful novel serum marker for evaluating the overall status of host cellular immunity (12).