Cytokines involved in the immunosuppressor period in experimental fasciolosis in rats

The aim of this study was to evaluate the kinetics of the cytokines interfe ron-gamma, interleukin-2, interleukin-10 and interleukin-4 produced by sple en mononuclear cells stimulated by Con A during an experimental infection i n rats with Fasciola hepatica. The proliferative response to Con A of Spm c ells from rats infected with F. hepatica was significantly decreased on day 7 post-infection (P < 0.006) and simultaneously an increase of interferon- <gamma>, interleukin-10 and interleukin-4 production along with a decrease of interleukin-2 by spleen mononuclear cells were observed. Interleukin-4 a nd interleukin-10 were involved in ablating cellular proliferation in vitro , as the addition of neutralising antibodies to either cytokine reversed th e proliferative block. The addition of exogenous recombinant interleukin-2 also restored the proliferative response by spleen mononuclear cells obtain ed 7 days after infection from infected rats. At the same time, we found an increase in interleukin-10 production by peritoneal cells (in close contac t with the flukes) and decreased nitric oxide levels. In addition, histolog ical studies on the liver on day 7 after infection showed the presence of p arasite inside migratory tunnels in the parenchyma, and polymorphonuclear l eukocytes, predominantly eosinophils, around the parasite. The transient su ppression in proliferative response mediated by cytokines interteukin-4 and interleukin-10 in the spleen, and diminution of nitric oxide production in the peritoneum could be mechanisms to evade the protective immune response during the first stages of liver penetration by the parasite, (C) 2001 Aus tralian Society for Parasitology Inc. Published by Elsevier Science Ltd. Al l rights reserved.