Figure 9A. Estimated proportions of PBMC subpopulations determined from cell-type deconvolution featuring transcriptional profiles upregulated in asymptomatic individuals. B-G. PBMCs from P. falciparum symptomatic (n=6) and asymptomatic (n=6) infected individuals as well as healthy immune controls (n=6) were stained with a panel of antibodies and analyzed by flow cytometry. tSNE plots (B) display cell density of the pooled data for each group, (C) shows a projection of the FlowSOM clusters on a tSNE plot, and (D) is a heatmap depicting the celluar phenotype of clusters of CTLA-4+CD3+CD19- cells. Bar plots representing mean relative abundance of biological replicates + SEM of relevant clusters among clinical groups (E), Mann-Whitney test, *p<0.05. The panel on the left shows the average CTLA-4 mean fluorescent intensity (MFI) or 6 biological replicates in cluster 4 + SEM, Mann-Whitney test, **p<0.01, while representative histograms of CTLA-4 expression in cluster 4 are shown on the right (F). Marker intensity within clusters 1 and 6 (G). H. C57BL/6 mice (n=10) were infected with P. chabaudi chabaudi. Percentage parasitemia of infected mice was determined every 2-3 days. Symbols represent average parasitemia + SEM. Splenocytes from P. chabaudi chabaudi infected mice were stained with fluorescent antibodies and analyzed by flow cytometry. (I) Representative contour plots showing CTLA-4-expressing cells among TREG and CD44+ CD4+ T cells. Splenocytes from P. chabaudi chabaudi infected mice were stained with fluorescent antibodies and analyzed by flow cytometry. (J, K) Percentage of CTLA-4+ cells among CD4+FoxP3+ Treg cells (J) and CD44+ activated CD4+ T cells (K) at peak (day 8 p.i) and recrudescent (day 20 p.i) parasitemia and after infection resolution (day 40 p.i). Bar plots represent mean percentage of 6 biological replicates + SEM (unpaired t-test, ***p<0.005, *p<0.05). Splenocytes from P. chabaudi chabaudi infected mice were stained with fluorescent antibodies and analyzed by flow cytometry. (L-N) tSNE plots (L) display cell density of the pooled data for each group, (M) shows a projection of the FlowSOM clusters on a tSNE plot, and (N) is a heatmap depicting the celluar phenotype of CTLA-4+ conventional CD4+ T cells during peak and recrudescent parasitemia. Splenocytes from P. chabaudi chabaudi infected mice were stained with fluorescent antibodies and analyzed by flow cytometry. (O) Bar plots represent the average relative abundance of 6 biological replicates in relevant clusters + SEM (unpaired t-test, **p<0.01). Splenocytes from P. chabaudi chabaudi infected mice were stained with fluorescent antibodies and analyzed by flow cytometry. Representative contour plots (P) of CTLA-4-expressing CD4+CD44+CCR7+CD62Lhigh central memory (CM) and CD4+CD44+CCR7-CD62Llow effector memory (EM) cells during peak and recrudescent parasitemia. Symbols represent the mean cell number of 6 biological replicates + SEM (unpaired t-test, ***p<0.05). Splenocytes from P. chabaudi chabaudi infected mice were stained with fluorescent antibodies and analyzed by flow cytometry. absolute number (Q) of CTLA-4-expressing CD4+CD44+CCR7+CD62Lhigh central memory (CM) and CD4+CD44+CCR7-CD62Llow effector memory (EM) cells during peak and recrudescent parasitemia. Symbols represent the mean cell number of 6 biological replicates + SEM (unpaired t-test, ***p<0.05). R. C57BL/6 mice (n=6) were infected with P. chabaudi chabaudi and treated with anti-CTLA-4 or isotype control every 3 days from day 13 p.i as indicated by the red arrows. Parasitemia was determined every 2-3 days. Bar plots represent mean parasitemia of biological replicates + SEM (unpaired t-test, **p<0.01, *p<0.05).