Histoplasma capsulatum fails to trigger release of superoxide from macrophages.

摘要: The yeast form of the dimorphic fungus Histoplasma capsulatum survives within macrophages after phagocytosis. To do so, it must avoid, inhibit, or resist a variety toxic oxygen metabolites. Using ferricytochrome c reduction to assay superoxide release, we examined response mouse various H. strains. Doses zymosan as low 20 particles per macrophage elicited superoxide, whereas failed induce even at 160 cells macrophage. This phenomenon was observed with two virulent strains (G217B and G186A) an avirulent variant G186A. Over 15- 150-min observation period, stimulated increasing c, but did not. When added concurrently zymosan, had no effect on production. Therefore, unable either inactivate radical inhibit host cell other competent stimuli. Enzymatically generated reduced in presence capsulatum, again implying that organism does not readily superoxide. experiment also demonstrated interfere used. Thus, rather than inhibiting generation inactivating anion, appear avoid effects by failing trigger its release.