FIG. 3.

Antigen-specific IFN-γ-producing cells are generated in the absence of CD4⁺ T-cell help following T. cruzi infection. Spleen cells were harvested from MHC II KO mice (black bars), wild-type mice (gray bars), and uninfected naïve mice (white bars) at days 15, 21, and 28 (D15, D21, and D28) postinfection. Frequencies of IFN-γ-producing CD8⁺ T cells were determined by intracellular cytokine staining after overnight in vitro stimulation with T. cruzi peptides, as described in Materials and Methods. Values represent the means ± SD of IFN-γ⁺ cells among CD8⁺ T cells (n = three mice per group) and are representative of two experiments. Statistically significant differences in IFN-γ production between B6.129 and MHC II KO mice are denoted by asterisks.