FIG. 2.

Kinetic and surface phenotype of splenic NKT cells during primary P. yoelii infection in C57BL/6 mice. (A) Numbers of total and CD4⁺ NKT cells in the spleens of B6 mice on day 0 (noninfected) and at days 6 and 10 after injection of 4,000 sporozoites. Splenic cells were stained with anti-NK1.1, anti-TCRβ, and anti-CD4 mAbs, and the numbers of total (NK1.1⁺ TCRβ⁺) and CD4⁺ (NK1.1⁺ TCRβ⁺ CD4⁺) NKT cells were determined by flow cytometry analysis. Data are representative of three independent experiments with at least three mice per time point. Results are expressed as mean values ± SD. (B) Flow cytometry analysis showing the level of surface expression of TCRβ and CD4 molecules on splenic CD4⁺ NKT cells (gate was done on NK1.1⁺ TCRβ⁺ CD4⁺ cells). Representative dot plots of data from infected mice on day 0 and day 10 are shown. (C) Markers expressed by splenic NKT cells in noninfected mice (day 0, filled histogram) and infected mice at day 6 (thin line) and day 10 (dotted line) after injection of 4,000 sporozoites. Splenic cells were stained with anti-NK1.1, -TCRβ, or -CD4 and anti-CD69, -CD62L, or -CD44 mAbs. Histograms are gated on CD4⁺ NKT cells as defined in A. Data are representative of two independent experiments with three mice per time point. *, the P value was <0.05 between control (day 0) and infected animals.