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Reactive nitrogen intermediates implicated in the inhibition of Encephalitozoon cuniculi (phylum microspora) replication in murine peritoneal macrophages
Author(s) -
DIDIER ELIZABETH S.
Publication year - 1995
Publication title -
parasite immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.795
H-Index - 75
eISSN - 1365-3024
pISSN - 0141-9838
DOI - 10.1111/j.1365-3024.1995.tb00908.x
Subject(s) - encephalitozoon cuniculi , microbiology and biotechnology , biology , macrophage , nitrite , lipopolysaccharide , interferon gamma , arginine , microspora , parasite hosting , in vitro , cytokine , immunology , biochemistry , microsporidia , spore , ecology , stamen , pollen , amino acid , microspore , world wide web , computer science , nitrate
Summary Encephalitozoon cuniculi (phylum microspora) is a protozoan parasite that can replicate within parasitophorous vacuoles in macrophages. Thioglycollate‐elicited BALBjc peritoneal macrophages treated with murine recombinant interferon‐γ (rIFN‐γ; 10u/ml) in combination with lipopolysaccharide (LPS; 10ng/ml) for 24 h killed E. cuniculi as determined by significant reductions in the number of parasites and percent of infected macrophages 48 h later compared with cultures treated with medium only. Treatment of the elicited macrophages with murine rIFN‐γ (10u/ml or 100u/ml) only, resulted in microbistatic activity. Significantly higher levels of nitrite (NO 2 ) were detected in supernatants from macrophage cultures treated with rIFN‐γ (10 u/ml or 100 u/ml) which induced microbistatic macrophage activity as well as from macrophage cultures treated with LPS + rIFN‐ when compared with levels of nitrite detected in supernatants of infected macrophages treated with medium only. Addition of the L‐ariginine analogue, N 3 monomethyl‐L‐arginine (NMMA) at concentrations of 50, 100 or 250 uM significantly inhibited nitrite synthesis and prevented microsporidia killing. Addition of exogenous L‐arginine at concentrations of 5mM or 10 mM reversed the NMMA‐induced inhibition of parasite killing. These results indicate that reactive nitrogen intermediates contribute to the killing of E. cuniculi by LPS + rIFN‐γ‐activated murine peritoneal macrophages in vitro.