Cytokine production by JE vaccine specific T cells by intracellular cytokine staining (ICS).

(A) Magnitude of T cell cytokine responses to JEV SA14-14-2 detected by flow cytometry/ICS in five participants showing positive responses. Data are the percentage of cells in the parent (CD4⁺/CD8⁺) gate staining for the indicated cytokine, above unstimulated values. Filled circles = CD4⁺ responses, open circles = CD8⁺ responses. Bars = median value of CD4⁺ responses only. (B) SPICE analysis of CD4⁺ T cell responses detected by flow cytometry. Data are the proportion of the response comprised of IFNγ⁺/IL2⁺/TNFα⁺ triple positive cells (red pie slices), double positive cells (yellow slices) and single positive cells (blue slices). Arcs indicate the proportion of the response producing individual cytokines: IFNγ (purple arcs), IL2 (green arcs) and TNFα (light grey arcs). Left pie chart: CD4⁺ responses at weeks 1–4 (n = 4), right pie chart: participant VA001/1 at week 16. Participant VA001/1 made a triple positive response at week 16 after vaccination, hence this participant is presented separately.