Intrinsic IL-2 Production by Effector CD8 T Cells Affects IL-2 Signaling and Promotes Fate Decisions, Stemness, and Protection

Here, we show that the capacity to manufacture IL-2 identifies constituents of the expanded CD8 T cell effector pool that display stem-like features, preferentially survive, rapidly attain memory traits, resist exhaustion, and control chronic viral challenges. The cell-intrinsic synthesis of IL-2 by CD8 T cells attenuates the ability to receive IL-2–dependent STAT5 signals, thereby limiting terminal effector formation, endowing the IL-2–producing effector subset with superior protective powers. In contrast, the non–IL-2–producing effector cells respond to IL-2 signals and gain effector traits at the expense of memory formation. Despite having distinct properties during the effector phase, IL-2–producing and nonproducing CD8 T cells appear to converge transcriptionally as memory matures to form populations with equal recall abilities. Therefore, the potential to produce IL-2 during the effector, but not memory stage, is a consequential feature that dictates the protective capabilities of the response.