Alfredo Castro

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

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 10 6 T. lewisi tripanomastigotes and 4 days later with 10 7 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), IFNγ 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.

Effect of Trypanosoma lewisi infection on the Toxoplasma gondii multiplication in white rat peritoneal macrophages

ABSTRACT Peritoneal macrophages (PM) from normal Wistar rats were treated in vitro with peritonealsupernatant or sera, obtained from rats infected with 10 6 Trypanosoma lewisi trypomastigotes beforethe infection with Toxoplasma gondii tachyzoites. In this experimental model, Toxoplasma multiplication in PM was increased, as compared to macrophages treated with supernatant or serafrom control rats not infected with T. lewisi . This effect was observed only if the active supernatantor sera came from rats infected with the T. lewisi 3 to 6 d before Toxoplasma inoculation.Furthermore, immunosuppressive activity was only detectable after at least 24 h incubation with thesupernatant or sera. These results are in accordance with our in vivo previous studies whichdemonstrated a clear immunosuppressive effect of T. lewisi during T.gondii infection of the remarkablyresistant Wistar rats. Key words : Immunosuppression, Toxoplasma gondii, Trypanosoma lewis i, peritoneal macrophages. INTRODUCTIONImmunosuppressive effects in parasiticinfections allow greater parasite multiplication inthe final host, causing important pathologydevelopment. That is the case of filariosis,schistosomosis, trichinosis and others diseases

Enfermedad de Chagas en Costa Rica: Estudio comparativo en dos épocas diferentes

.Como no se han realizado encuestasepidemiologicas completas de esta enfermedadde Chagas, el concepto generalizado en lasautoridades de Salud es que esta parasitosis noes importante en el pais. Esto se debe tal vez a laexistencia de pocos casos humanos realmentecomprobados de la misma. Este hecho me ncionadopor el Dr. Morera en la reunion del TDR sobre