Glucocorticoid-mediated Suppression of Effector Programming Assists the Memory Transition of Virus-specific CD8+ T Cells.

We demonstrate the role of signaling via the glucocorticoid receptor, NR3C1, in differentiation of CD8+ T cell memory. Pharmacological inhibition as well as the short hairpin RNA-mediated knockdown of the receptor hindered memory transition and limited the homeostatic turnover of the activated CD8+ T cells. Dexamethasone exposure of CD8+ T cells expanded during a resolving infection with influenza A virus or a γ-herpesvirus promoted conversion of effector cells into memory cells by modulating cellular metabolism and lowering the accumulation of reactive oxygen species. Reduced reactive oxygen species levels in the responding effector cells upregulated Bcl2 and enhanced survival. The generated virus-specific memory CD8+ T cells were efficiently recalled following challenge of animals with a secondary infection to control it better. The memory-enhancing effect was predominantly evident at low doses of dexamethasone. Therefore, controlled glucocorticoid signaling within the effector CD8+ T cells is crucial for optimal memory differentiation.