(A) Daily parasitemia and survival rates of C57BL/6 mice depleted of CD8+ or CD4+ T cells after infection with PyNL. Parasitemia was estimated from microscopic observation of Giemsa-stained blood films. Parasitemia values are means ± SE of three pooled experiments (control: N = 20; CD4 depletion: N = 20; CD8 depletion: N = 23). *p < 0.05, **p < 0.01, and ***p < 0.001, Mann–Whitney U-test. Survival rate was calculated from three pooled individual experiments, as described above. p values for the Kaplan–Meier log rank test are shown. (B) Flow-cytometric analyses of splenic CD8+ T cells were performed 7 days after infection with PyNL. Single-cell suspensions from spleens were stained with fluorescence-labeled anti-CD8β antibody. CD8+ T cells were analyzed for the expression of the indicated molecules. Shaded areas and lines in the histograms represent their expression in uninfected and infected mice. Bar graph indicates percentages of CD8+ T cells expressing the molecules as means ± SD of five mice from one of three experiments. *p < 0.05, **p < 0.01, Mann–Whitney U-test. (C) Daily parasitemia (upper panel) and survival rates (bottom panel) of wild type mice (WT) or gld mice infected with PyNL, monitored as in Figure 1A. WT, N = 6; gld, N = 9. Parasitemia values are means ± SD from one of five experiments. *p < 0.05 and ***p < 0.001, Mann–Whitney U-test. Survival rates are from five pooled individual experiments (WT, N = 28; gld, N = 25). (D) Contribution of FasL expressed on CD8+ T cells to the protective effects against blood-stage malaria. Expression of FasL on splenic CD4+ T cells was evaluated. *p < 0.05, Mann–Whitney U-test. Data of FasL on CD8 are the same experiment as Figure 1B. (E) Experimental protocol for the adaptive transfer of cells after the prime–boost PyNL vaccine regime against lethal PyL infection. WT and gld mice were infected with PyNL, and then boosted twice with PyL. CD4+ and CD8+ T cells isolated from the vaccinated donors were transferred into irradiated recipients. Note that although some gld mice died from the PyNL infection, the survivors were as resistant to PyL infection as the WT mice. (F) Parasitemia was monitored in the recipients of the indicated cells. Each symbol indicates means ± SD. Each group contained five mice. The final survival rate of each group is also indicated. The results are from one experiment, representative of the two performed. Dagger indicates death.