Loss of the orphan nuclear receptor NR2F6 enhances CD8⁺ T-cell memory via IFN-γ

Memory formation is a hallmark of T cell-mediated immunity, but how differentiation into either short-lived effector cells (SLECs, CD127^-KLRG1⁺) or memory precursors cells (MPECs, CD127⁺KLRG1^-) and subsequent regulation of long-term memory is adjusted is incompletely understood. Here, we show that loss of the nuclear orphan receptor NR2F6 in germ-line Nr2f6-deficient mice enhances antigen-specific CD8⁺ memory formation up to 70 days after bacterial infection with Listeria monocytogenes (LmOVA) and boosts inflammatory IFN-γ, TNFα, and IL-2 cytokine recall responses. Adoptive transfer experiments using Nr2f6^-/- OT-I T-cells showed that the augmented memory formation is CD8⁺ T-cell intrinsic. Although the relative difference between the Nr2f6^+/+ and Nr2f6^-/- OT-I memory compartment declines over time, Nr2f6-deficient OT-I memory T cells mount significantly enhanced IFN-γ responses upon reinfection with increased clonal expansion and improved host antigen-specific CD8⁺ T-cell responses. Following a secondary adoptive transfer into naïve congenic mice, Nr2f6-deficient OT-I memory T cells are superior in clearing LmOVA infection. Finally, we show that the commitment to enhanced memory within Nr2f6-deficient OT-I T cells is established in the early phases of the antibacterial immune response and is IFN-γ mediated. IFN-γ blocking normalized MPEC formation of Nr2f6-deficient OT-I T cells. Thus, deletion or pharmacological inhibition of NR2F6 in antigen-specific CD8⁺ T cells may have therapeutic potential for enhancing early IFN-γ production and consequently the functionality of memory CD8⁺ T cells in vivo.