Early and transient cytotoxic response of peritoneal cells from Fasciola hepatica-infected rats.
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 microM and all juvenile flukes were killed by a 90 microM NO exposition (Lethal Dose 50 between 45.8 and 50.3 microM, 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.
Sibille
Pierre
P
INRA Tours, BioAgresseurs, Santé, Environnement, 37380 Nouzilly, France. Sibille@tours.inra.fr
Tliba
Omar
O
Boulard
Chantal
C
D000818:Animals; D005210:Fasciola hepatica / Q000276:immunology*; D005211:Fascioliasis / Q000276:immunology* / Q000469:parasitology; D005260:Female; D005609:Free Radicals / Q000378:metabolism; D017737:Macrophages, Peritoneal / Q000276:immunology; D008297:Male; D009569:Nitric Oxide / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar
D005609:Free Radicals; D009569:Nitric Oxide