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Microbicidal activity of eosinophils is associated with activation of the arginine‐NO pathway
Author(s) -
Sandra Helena Penha de Oliveira,
Simone Gonçalves Fonseca,
Pedro Roosevelt Torres Romão,
Florêncio Figueiredo,
Sérgio Henrique Ferreira,
Fernando Cunha
Publication year - 1998
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 - 10.1046/j.1365-3024.1998.00159.x
Subject(s) - nitrite , eosinophil , nitric oxide synthase , nitric oxide , stimulation , biology , leishmania major , immunology , tumor necrosis factor alpha , omega n methylarginine , chemokine , microbiology and biotechnology , leishmania , immune system , endocrinology , nitrate , parasite hosting , ecology , asthma , world wide web , computer science
In order to investigate the ability of rat peritoneal eosinophils to produce nitric oxide (NO) induced by cytokines in vitro , these cells were activated with several cytokines (IL‐5, IL‐8, Rantes, TNF‐α, IFN‐γ) in association or not with LPS. Under these conditions, we were able to detect nitrite in the incubation medium when the eosinophils were stimulated with IFN‐γ or IL‐8 in the presence of LPS. LPS alone also induced nitrite production. Significant levels of nitrite in the medium were already present after 12 h of stimulation and increased steadily within the next 48 h. Regarding NO synthase, its highest activity was achieved at 12 h after IFN‐γ/LPS stimulation. After this peak, the enzymatic activity reduced gradually to control levels 48 h after the stimulation. The simultaneous addition of the NO synthase inhibitor L‐NIO (100 μM) to the eosinophil suspension blocked nitrite production and NO synthase activity. On the other hand, neither IL‐5, Rantes nor TNF‐α were able to induce the release of nitrite in the presence or absence of LPS. To evaluate the microbicidal effect of these cells against the Leishmania parasite, eosinophils were infected with Leishmania major . It was observed that these cells were able to produce nitrite and to kill the parasite after activation with LPS/IFN‐γ. Moreover, L‐NIO blocked this leishmanicidal activity and the nitrite production. Our results suggest that activated eosinophils release NO which is involved in their microbicidal activity against Leishmania major.