Figure 1.

Frequency of Plasmodium falciparum–specific CD4⁺ T-cell responses is dependent on exposure intensity. A, Gating strategy to identify CD4⁺CD45RA⁻ cytokine cells producing interferon γ (IFN-γ), interleukin 2 (IL-2), interleukin 10 (IL-10), and tumor necrosis factor α (TNF-α) following stimulation with P. falciparum–infected red blood cells (RBCs). Background responses (to uninfected RBCs) were subtracted from each Boolean gate. B, Frequencies of CD4⁺ T cells producing any cytokine in response to P. falciparum–infected RBC stimulation are shown separately for children and adults from Walukuba (low-transmission setting) and Nagongera (high-transmission setting). C, The proportions of children and adults with a detectable CD4⁺ T-cell response to P. falciparum were higher in Nagongera, compared with Walukuba. Abbreviations: FSC, forward scatter; SSC, side scatter.