PD-1 expression is up-regulated on CD4 and CD19 positive cells during acute <i>P. falciparum</i> infection in children.

<p>A. Flow cytometry plots demonstrating increased expression of PD-1 on CD4⁺ T-cells (top row) and CD19 positive cells (bottom row) on Day 0 (black) compared to Day 28 (white). B. The percentage of programmed death-1 (PD-1) expressing, CD4 and CD19 positive cells in acute uncomplicated P. <i>falciparum</i> malaria infection (white box), on convalescence in the same donors (black box) and in age- and sex- matched healthy controls (grey box). C. The absolute number of programmed death-1 (PD-1) expressing, CD4 and CD19 positive cells in acute uncomplicated P. <i>falciparum</i> malaria infection (white box), on convalescence in the same donors (black box) and in age- and sex- matched healthy controls (grey box). All gates were set using appropriate isotype controls. ^a<i>P</i> values calculated using Wilcoxon rank comparison of matched pairs. ^b<i>p</i> values calculated using Mann-Whitney U statistical comparison of unmatched pairs.