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Vet. Res.
Volume 35, Number 5, September-October 2004
Page(s) 573 - 584
How to cite this article Vet. Res. (2004) 573-584
Vet. Res. 35 (2004) 573-584
DOI: 10.1051/vetres:2004033

Early and transient cytotoxic response of peritoneal cells from Fasciola hepatica-infected rats

Pierre Sibille, Omar Tliba and Chantal Boulard

INRA Tours, BioAgresseurs, Santé, Environnement, 37380 Nouzilly, France

(Received 2 December 2003; accepted 24 March 2004)

Abstract - Experimental infection by F. hepatica was performed on rats. Early recruitment of the peritoneal cell population was observed and revealed transient parasite-killing activity, preceded and followed by a state of total unresponsiveness. The activation peaked at seven days post-infection (dpi) and was characterised by a massive peritoneal cell recruitment, a strong superoxide anion and nitric oxide (NO) production, that were coincident with the fasciolicide activity of these cells, as monitored by an in vitro decrease of juvenile fluke viability in a conditioned medium. The addition of L-NG-monomethyl arginine (LNMMA) to cell cultures abrogated both fasciolicide activity and NO production. Parasites started to die when NO production exceeded 25  $\mu$M and all juvenile flukes were killed by a 90  $\mu$M NO exposition (Lethal Dose 50 between 45.8 and 50.3  $\mu$M, 95% fiducial limits). However, when rat peritoneal cells were cultured in the presence of either infected or control rat serum, juvenile flukes were much more resistant to the oxidative burst, despite a massive attachment of rat peritoneal cells to the parasite tegument. These data suggest that a transient control of fasciolosis may take place in the peritoneum following the parasite intrusion but that the parasite efficiently scavenges the host cellular response to avoid destruction.

Key words: F. hepatica / rat peritoneal cells / cytotoxicity / nitric oxide

Corresponding author: Pierre Sibille

© INRA, EDP Sciences 2004