Differential release of tumor necrosis factor-α from murine peritoneal macrophages stimulated with virulent and avirulent species of mycobacteria |
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Authors: | Valeria Falcone Effiong B. Bassey Antonio Toniolo Pier Giulio Conaldi Frank M. Collins |
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Affiliation: | Institute of Medicine and Public Health, University of Pavia, Viale Borri 57, 21100 Varese, Italy;Trudeau Institute Inc., 12983 Saranac Lake, NY, USA |
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Abstract: | Abstract The ability of Mycobacterium tuberculosis H37Rv and H37Ra, M. bovis BCG and M. smegmatis to induce the secretion of tumor necrosis factor-α (TNF-α) by cultured murine peritoneal macrophages is inversely related to their virulence. The avirulent species of mycobacteria which were unable to persist in macrophages were capable of inducing significant levels of TNF-α compared to that formed in cultures infected with the virulent M. tuberculosis H37Rv. This difference was also associated with an inherent toxicity by live H37Rv for macrophage cultures. Heat-killed H37Rv was non-toxic and induced significant levels of TNF-α; in contrast, live and heat-killed suspensions of avirulent mycobacteria had an equivalent ability to trigger TNF-α secretion. The TNF-α response was dose-dependent, related directly to the percentage of infected cells, and peaked 6–12 h post-infection. An early and vigorous TNF-α response appears to be a marker of macrophage resistance, while the downregulation of this response seems associated with macrophage toxicity and unrestricted mycobacterial growth. |
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Keywords: | Mycobacteria Tumor necrosis factor-α Virulence Macrophage |
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