Fig. 5

CD70 expression correlated with activation-induced phosphorylation of ERK1/2. A A representative flow cytometry plot of ERK1/2 phosphorylation in CD70⁺ and CD70^- CD8⁺ memory T cells before and after anti-CD3/CD28 stimulation in vitro at 5 and 30 minutes. Isolated CD8⁺ T memory cells were treated with anti-CD3/CD28 for indicated time and cells were then fixed and stained for CD70 and phosphorylated ERK1/2. B Percentage of phosphorylated ERK1/2 positive in CD70⁺ and CD70^- CD8⁺ T memory cells. The data were the average of four independent experiments. C ERK1/2 phosphorylation in CMV- and IAV-specific CD8⁺ T_CM cells after anti-CD3/CD28. 1 x 10⁴ sorted CMV- and IAV-specific CD8⁺ T_CM cells (N=7) were stimulated with anti-CD3/CD28 for 15 min, fixed with PFA, permeabilized with cold methanol, and stained with antibody against phosphorylated ERK1/2 (2 x 10⁵ 293T cells were added to reduced cell loss during centrifugation). Percentages of phosphorylated ERK1/2 positive antigen-specific CD8⁺ T_CM cells were back-calculated based on the ratio between antigen-specific CD8⁺ T_CM cells and 293T cells. * Indicates P < 0.05, ** indicates P < 0.01