Antiplasmodial activity of Vγ9Vδ2 T cells in PBMCs and as purified T-cell lines. (A) Undepleted PBMCs (total PBMCs) or Vδ2⁺ T cell–depleted PBMCs (Vδ2-depleted PBMCs) from 8 different healthy donors were activated with BrHPP (400nM) or left untreated for 40 hours and then cocultured in a standard parasite inhibition assay at a 4/1 E/T ratio with a synchronized trophozoite culture for 24 hours. At the end of this period, parasitemia in cocultured samples was compared with that in synchronized trophozoite cultures incubated without PBMCs by hydroethidine staining. The percentage of Vδ2⁺ CD3⁺ cells among total PBMCs varied among the donors (from 0.5% to 1.9%). Data represent the parasitemia (means of duplicates) of cocultures with PBMCs of each donor tested (n = 8; *P ≤ .05 by the Wilcoxon signed ranked test). (B) Short-term Vγ9Vδ2 T-cell lines (STL) were tested after a 24-hour priming with no cytokine added or with IL-2 (20 IU/mL) only or with IL-15 (50 ng/mL) and cocultured with the parasites at a 4/1 E/T ratio in a standard parasite inhibition assay. Data represent the mean parasitemia in the various cocultures conditions (n = 10 STL; **P ≤ .01 for Wilcoxon signed ranked test comparisons). (C) S1 and the JT long-term Vγ9Vδ2 T-cell lines were (i) primed for 24 hours with IL-2 (20 IU/mL) and increasing doses of IL-15 and cocultured with the parasites at a 4/1 E/T ratio or (ii) primed for 24 hours with IL-2 (20 IU/mL) with or without added IL-15 (50 ng/mL) and cocultured with the parasites at increasing E/T ratios as indicated. Graphs represent the mean of parasitemia ± SD of 4 independent experiments (n = 4; *P ≤ .05 and **P ≤ .01 by Mann-Whitney rank sum test; ns indicates not significant).