FIG. 8.

Measurement of NO and IFN-γ induced by T cells from mice chronically infected with T. cruzi. To establish chronic infections, mice were injected with five Peru strain trypomastigotes. At 3 months postinfection, mice were given a challenge infection of 10³ trypomastigotes. Two weeks after the boost, T cells were isolated by nylon wool nonadherence. T cells from chronic mice and naive mice were cultured with PFR protein (gray bars), TolT protein (white bars), or no antigen (black bars) in the presence of IC-21 macrophages. Supernatants were removed from cultures at days 4 and 7 and assayed for IFN-γ (A) and nitrite (B). μm, micromolar. Bars represent average values ± standard deviations obtained from triplicate cultures.