Figure 6. The role of common γ-chain signaling and neutrophils in protection against secondary exposure to P. yoelii.

BALB/c or γ^−/− mice were immunized i.m. with Ad-M PyMSP1₄₂, challenged at Week 10 with 10⁶ P. yoelii 17XNL pRBCs and then rechallenged at Week 18 with 10⁶ P. yoelii YM pRBCs. One day before and 3 days after secondary challenge, six BALB/c and six γ^−/− mice were given 0.5 mg 1A8 i.p. (PMN⁻), and all other mice—WT and γ^−/−—were given 0.5 mg i.p. control rat IgG. (A) Representative flow plots showing granulocytes from the blood and spleen of BALB/c mice treated in parallel with challenged mice on Days 1 and 7 following 1A8 or control rat IgG treatment. Plots thus represent inferred PMN⁻ in challenged mice. Flow data acquisition was normalized by setting stopping gates at 10⁴ or 10⁵ CD8⁺ cells for blood and spleen samples, respectively. Boxes and numbers indicate the neutrophil population and their percentage make-up of the granulocyte population. (B) AUC analysis of parasitemia for Days 3–6 following secondary challenge of nonimmunized (●) and immunized (○) groups. Lines on dot plot represent medians.