Fig. 2.

Memory phenotype of P. falciparum-specific CD4 ⁺ T cell population maintained in absence of continual exposure. Differential expression of CCR7, CD27, and CD45RO by P. falciparum-specific CD4⁺ T cells (producing IFN-γ upon stimulation with P. falciparum-infected red blood cells). Each phenotype (defined by a specific combination of markers) is shown beneath the X-axis. Where a specific phenotype has been ascribed to a particular differentiation stage, this is specified. T_CM and T_EM refer to central memory and effector memory cell populations, respectively. The frequency of each subset is expressed as a percentage of the total IFN-γ⁺ CD4⁺ T cell population and was compared between historically exposed children (Ngerenya) and continually exposed children (Junju). Horizontal black lines represent median responses in each group. Mann–Whitney U-test was used for pairwise analysis of differences between groups – no significant differences were observed. Pie charts illustrate relative proportions of each of the combinations of markers in the two groups of children