Role of interferon - γ on the immunosuppression during Toxoplasma gondii infection by Trypanosoma lewisi

Abstract

On the basis of previous studies on Trypanosoma lewisi immunosuppression model groups of 5 Wistar rats were infected with. T. gondii and T. lewisi according to the following protocol. One group was inoculated i.p. with 106 T. lewisi tripanomastigotes and 4 days later with 107 T. gondii tachyzoites. The second and third groups were infected only with T. lewisi or T. gondii respectively. The fourth group was not infected and served as control. Rats were bled before the infection and then every day for seven days. Serum samples were collected and the levels of IFN-γ, IL-2 and TNF-α were measured. The results indicates that the level of IFN-γ is very high 24 hour after infection in rats inoculated with T. gondii only, while in those animals infected with both parasites (first group), IFN-γ was not detected 24 hours after infections with T. gondii. These data give evidence that a reduction of IFN-γ levels is one of the reasons for the immunosuppressive effect induced by T. lewisi, increasing T. gondii multiplication in an animal as the rat, which is remarkable resistant to this parasite.