Figure 6.

Induction of phosphorylation of signal transducer and activator of transcription (STAT) proteins in activated CD8⁺ T cells following interleukin-21 (IL-21) stimulation. The cord blood mononuclear cells were activated with anti-CD3 and anti-CD28 for 2 days, rested overnight, and restimulated with or without IL-21 for 15 min. Cells were then harvested and expression of phosphorylated STAT1, -3, -4, -5 or -6 was determined by flow cytometry. Cells were first gated on CD8⁺ T cells and subsequently analysed. Filled histograms represent expression of phosphorylated STATs in unstimulated cells; open histograms represent expression of phosphorylated STATs in the presence of IL-21 (upper panel). The results of three separate experiments are shown (lower panel).