Splenic NK, NKT, γδT and CD4 T lymphocytes produce IFN-γ simultaneously at day 5 p.i. Splenocytes were isolated from non-infected and infected B6 mice at days 4, 5, 6, and 7 after injection of 4,000 P. yoelii 265BY sporozoites. Intracellular expression of IFN-γ among NK cells (gated on NK1.1+CD3-), NKT cells (gated on NK1.1+TCRβ+), γδT cells (gated on CD3+TCRγδ+), CD4 T cells (gated on CD4+) and CD8 T cells (gated on CD8+) cells was analysed by flow cytometry. A. FACS dot plots showing IFN-γ expression among splenic NK, NKT and γδT cells at days 0 and 5 p.i. IC: isotype-matched control antibody. Percentages of positive cells are indicated. B and C. Kinetics of intracellular IFN-γ expression among the different subsets of lymphocytes. Analysis was performed as shown in A. Results are expressed as mean values ± SD of the percentages (B) or the numbers (C) of IFN-γ-positive cells among each subset. Data are representative of two independent experiments with at least three mice per time point.