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. 2004 Oct 25;101(45):16004–16009. doi: 10.1073/pnas.0407192101

Fig. 3.

Fig. 3.

Chronic memory CD8 T cells respond poorly to IL-7 and IL-15. (A) Acute memory (day 180) or chronic memory (day 240) CD8 T cells were CFSE-labeled and tested for responsiveness to IL-7 and IL-15 in vitro (5 ng/ml each). Division was assessed after 60 h. Numbers indicate the percent of D/bGP33+ CD8 T cells that had divided at least once. (B) Acute memory (day 140) and chronic memory (day 115) CD8 T cells were purified and labeled with CFSE, and equal numbers of Db/GP33+ cells were cotransferred into naïve recipients. IL-15 was injected i.p. daily (5 μg per injection), and division of Db/GP33+ CD8 T cells was analyzed on day 5. (C) IL-7 and IL-15 receptors on acute memory (day 150) and chronic memory (day 120) CD8 T cells. Histograms are gated on Db/GP33+ CD8 T cells. (D) Staining for intracellular pSTAT5 and Bcl-2 expression in the same populations as in C. For all panels similar results were observed for the LCMV Db/GP276+ CD8 T cell population (data not shown). The lower expression of cytokine receptors (except CD132 and IL-15Ra) and intracellular molecules by chronic memory Db/GP33+ CD8 T cells was statistically significant (Fig. 6).