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Category: Fungi and Fungal Pathogenesis; Clinical Microbiology
T-Cell Responses and Cytokines, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555818357/9781555819101_Chap25-1.gif /docserver/preview/fulltext/10.1128/9781555818357/9781555819101_Chap25-2.gifAbstract:
The immune response to tuberculosis is a double-edged sword that may contribute to both clearance of infection and tissue damage. In addition, recent evidence suggests that tuberculosis promotes progression of disease due to human immunodeficiency virus (HIV). Most persons who become infected with Mycobacterium tuberculosis mount a protective immune response and remain clinically well, the only evidence of infection being development of a positive tuberculin skin test. Disseminated tuberculosis reflects an ineffective immune response, manifested by a high frequency of negative tuberculin skin tests and failure of T lymphocytes to proliferate in vitro in response to M. tuberculosis antigens. Tumor necrosis factor (TNF) synergizes with gamma interferon to increase production of nitric oxide metabolites and mycobacterial killing and is essential for granuloma formation to contain mycobacterial infection. Published data on cytokine production by human T cells in response to M. tuberculosis are conflicting. In patients with tuberculous pleuritis, expression of mRNA for the Th1 cytokines gamma interferon and IL-2 is greater in pleural fluid mononuclear cells than in blood mononuclear cells, and concentrations of gamma interferon are 15-fold higher than those in serum. More comprehensive studies are needed to assess the role of CD8+ cells in human antituberculosis defenses. One strategy for developing antituberculosis vaccines is to characterize the T cells and cytokines that mediate clearance of bacilli during the primary immune response as well as the memory T-cell subpopulations and cytokines that protect against tuberculosis from exogenous reinfection and endogenous reactivation.
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Cytokine patterns in mycobacterial disease. Reverse transcriptase polymerase chain reaction was used to quantify cytokine mRNA in skin lesions of patients with tuberculoid and lepromatous leprosy. Type 1 cytokines predominate in tuberculoid lepromatous patients, whereas type 2 cytokines are dominant in patients with lepromatous leprosy. IFN-γ, gamma interferon.
Cytokine patterns in mycobacterial disease. Reverse transcriptase polymerase chain reaction was used to quantify cytokine mRNA in skin lesions of patients with tuberculoid and lepromatous leprosy. Type 1 cytokines predominate in tuberculoid lepromatous patients, whereas type 2 cytokines are dominant in patients with lepromatous leprosy. IFN-γ, gamma interferon.
Cytokines produced by macrophages and by Th1 and Th2 cells
Cytokines produced by macrophages and by Th1 and Th2 cells