Production of interleukin-18 in human tuberculosis

To investigate the role of interleukin (IL)-18 in human tuberculosis, IL-18 production was evaluated in blood and at the site of disease in patients w ith tuberculosis. Mycobacterium tuberculosis-stimulated peripheral blood mo nonuclear cells (PBMC) from tuberculosis patients secreted less IL-18 and i nterferon-gamma (IFN-gamma) than did PBMC from healthy persons reactive to tuberculin, M, tuberculosis-induced IFN-gamma production was inhibited by a nti-IL-18 and enhanced by recombinant IL-18, Alveolar macrophages secreted IL-18 in response to M. tuberculosis, and IL-18 and IFN-gamma concentration s were higher in pleural fluid of patients with tuberculosis than in pleura l fluid of patients with nontuberculous diseases. These findings demonstrat e that IL-18 production by PBMC correlates with IFN-gamma production and ef fective immunity to tuberculosis, suggesting that IL-18 contributes to a pr otective type 1 cytokine response in persons with mycobacterial infection.