Figure 4. Helpless CD8⁺ T cells do not limit liver stage parasite development.

Control and CD4-depleted BALB/c mice received TCR-Tg cells and were then immunized with γ-spz. To evaluate protection, mice were challenged with 2×10⁴ live sporozoites twelve days after immunization. Forty hours after challenge, livers were excised and control of parasite development was evaluated by quantitative PCR for P. yoelii 18S rRNA. (A) Mice were depleted of CD4⁺ cells prior to immunization or were depleted of CD8⁺ cells on day 10 after immunization. (B) Mice were depleted of CD4⁺ cells either three days prior to (“Before”) – or ten days after (“After”) γ-spz immunization. Dashed horizontal lines represent limit of detection for the individual experiment. *, p<0.05; **, p<0.01, Mann-Whitney test. Bars represent mean ± SEM of 4–5 mice per group and are representative of two independent experiments with similar results.