Fig. 1

P. falciparum-specific CD4⁺ T cells are maintained in the absence of continual exposure to P. falciparum. a Gating strategy to identify live CD4⁺ T cells. b Intracellular cytokine staining assay demonstrating CD4⁺ T cell response of one representative child to stimulation with P. falciparum-infected RBCs (iRBC), negative controls: media and uninfected RBC (uRBC) and positive control: plate-bound anti-CD3 (α-CD3). Shown is CD4⁺ T cell production of IFN-γ and IL-10 (upper panel) as well as IL-4 and TNF-α (lower panel). c Overall frequency of CD4⁺ T cells producing any cytokine, IFN-γ, TNF-α, IL-10, and IL-4, respectively. P. falciparum-specific cytokine production was calculated as percentage of CD4⁺ T cells producing a particular cytokine following iRBC stimulation minus uRBC stimulation. Blue dots represent historically-exposed children living in Ngerenya (n = 44), while red squares represent continually exposed children living in Junju (n = 44). Horizontal black lines indicated the median response for each group. No statistically significant differences were observed between historically and continually exposed children, as assessed by Mann–Whitney U test