Figure 2.

STAT3 inhibits CD8⁺ T cell proliferation and protects T cells from apoptosis. (a, b) WT or STAT3KO naïve T cells were stimulated with anti-CD3/CD28 Abs under nonpolarizing condition for 4 days, and IL-2 or IFN-γ expression was detected and quantified by the intracellular cytokine staining assay (a) or RT-qPCR (b). (c) WT or STAT3KO T cells were stimulated in vitro with anti-CD3/CD28 Abs, and CFSE dilution analysis was performed after 4 d stimulations. (d) Naïve CD8⁺ T cells were cultured under Tc0 or Tc1 condition for 4 days and stained with Annexin-V and 7-AAD. The cells undergoing apoptosis or necrosis were detected by FACS and cell counting using Vi-Cell XR cell-viability analyzer. (e) The relative percentages of apoptotic and viable cells were derived from the data shown in Figure 2(d) and statistically analyzed with Student's t-test. Results are representative of 3 independent experiments.