Interferon-gamma levels during the course ofTrypanosoma cruzi infection ofCalomys callosus (Rodentia-Cricetidae) and Swiss mice

Abstract

Serum levels of interferon-gamma (IFN-gamma) were evaluated in Calomys callosus and Swiss mice during the course of infection by four strains of Trypanosoma cruzi. All strains stimulated the production of this interleukine; however, the timing of its onset and permanence varied among strains and between the two animal models. When chronically infected animals with no detectable serum IFN-gamma were challenged with the homologous strain, they produced quantities comparable with those obtained during the acute phase of infection. In C. callosus there was a correlation between H2O2 liberation by peritoneal macrophages and serum IFN-gamma levels, whereas no such correlation was found in mice. C. callosus had a higher capacity to heal histopathological lesions, whereas lesions in mice were progressive. The results obtained suggest that C. callosus develops well-adapted immune mechanisms that may be important for its role as a reservoir of T. cruzi.

Participation of cytokines in the necrotic-inflammatory lesions in the heart and skeletal muscles of Calomys callosus infected with Trypanosoma cruzi

“…These observations were associated with in situ expression of TNF-α and IFN-γ. Probably the TNF-α and IFN-γ are mediating parasite disintegration by macrophage activation, with release of O metabolites such as H 2 O 2 , as demonstrated by Borges et al (1995). In the present study it has been demonstrated that IFN-γ persists in C. callosus tissues for a prolonged time (65 days) as compared with the other cytokines that were absent in the heart and skeletal muscle at this phase.…”

“…In previous studies (Borges et al 1995), evaluation of IFN-γ levels in C. callosus infected with T. cruzi, was performed by titration of antiviral activity on L-929 cells, by using a stan-dard encephalomyocarditis virus cytopathic-effectinihibiton. To characterize the antiviral activity, serial dilutions of serum samples were incubated with anti-murine IFN-γ monoclonal antibody.…”

“…In the present study it has been demonstrated that IFN-γ persists in C. callosus tissues for a prolonged time (65 days) as compared with the other cytokines that were absent in the heart and skeletal muscle at this phase. Serum levels of IFN-γ were evaluated in C. callosus and Swiss mice, infected with different strains of T. cruzi (Borges et al 1995), in an attempt to correlate this cytokine with the control of infection in vivo. The highest IFN-γ serum levels in C. callosus, were obtained with strain F (Biodeme Type III, T. cruzi I), with peak at 7-day and with titers maintaining a plateau until day 28 and dropping after that to baseline levels.…”

“…In previous investigations Borges et al (1995) have demonstrated the increase of IFN-γ levels in the serum of C. callosus acutely infected with a sylvatic strain of T. cruzi (M226). In the infection with others strains of T. cruzi, the levels of serum IFN-γ were high in the acute phase, with positive correlation with H 2 O 2 liberation by peritoneal macrophages and it was associated with the decrease of parasitemia (Borges et al 1995).…”

“…In the infection with others strains of T. cruzi, the levels of serum IFN-γ were high in the acute phase, with positive correlation with H 2 O 2 liberation by peritoneal macrophages and it was associated with the decrease of parasitemia (Borges et al 1995). The referred authors concluded that during the acute phase of the infection, the C. callosus develops a T-cell dependent immune response characterized by the production of IFN-γ with regulation of parasitemia to low levels, and controlling tissue parasitism without resulting in host-tissue aggression.…”