FIG 4.

Assessing the role of CD4⁺ and CD8⁺ T cells in vaccine-induced protection following homologous challenge. (A to D) Parasitemia (A), hemoglobin levels (B), clinical scores (C), and survival (D) in BALB/c mice that received three doses of 10⁶ chemically attenuated P. yoelii 17X pRBCs, followed by intraperitoneal injections of rat Ig, anti-CD4, anti-CD8, or a combination of anti-CD4 and anti-CD8 antibodies on days −3, −2, −1, 0, 7, 15, and 22 relative to challenge with 10⁵ P. yoelii 17X pRBCs on day 0. A naive control group was also included. The group that received rat Ig contained nine mice; all other groups contained ten mice. Error bars show the SEM for each group. +, mice that succumbed to infection.