Figure 1. STAT3-deficient memory CD8⁺ T cells sustain a terminally differentiated effector phenotype.

(A) Stat3^+/+ (filled square) and Stat3^−/− (open circle) mice were infected with LCMV, and D^bGP_33–41-specific CD8⁺ T cells in spleen were enumerated at day 8, 40 and 80 p.i. (B) Bar graphs show viral titers in the serum at day 8 p.i. LOD denotes the level of detection. Serum from naïve mice infected with CL13 served as a positive control. (C) Dot plots show expression of KLRG1 and IL-7R in D^bGP_33–41 tetramer⁺ CD8⁺ T cells at day 8 and 80 p.i. (D) Numbers of KLRG1^lo IL-7R^hi and KLRG1^hi IL-7R^lo subsets from (A and B) were plotted in line graphs. (E) Histograms show the expression level of CD27, CD122, Granzyme B and BCL-2, and percentage of CD62L⁺ and IL-2⁺ in D^bGP_33–41 tetramer⁺ Stat3^+/+ (shaded histogram) and Stat3^−/− (dashed line histogram) CD8⁺ T cells at day 80 p.i. (F) Dot plots show the IFNγ and TNFα expression in GP_33–41 peptide stimulated Stat3^+/+ and Stat3^−/− splenocytes at day 80 p.i. Data shown are representative of at least three independent experiments per time point. MFI or percentage of “positive” cells (mean±SEM) shown in the upper left or right corner throughout the whole manuscript.