Epigenetic training licenses naïve CD8⁺ T cell metabolic fitness and function

We identify histone variant H2A.Z as a key regulator of an epigenetic training program that licenses quiescent naïve CD8+ T cells for future activation. H2A.Z deficiency disrupts naïve T cell homeostasis and effector responses.

Multi-omics reveals that H2A.Z is selectively deposited at OXPHOS gene promoters in quiescent naïve CD8+ T cells, priming the chromatin for rapid transcriptional induction. This training is developmentally instructed by tonic IL-7 signaling and regulated by transcription factor GABPα. Age-related decline in IL-7 signaling reduces H2A.Z occupancy and impairs T cell activation, while IL-7 supplementation or enforced H2A.Z expression rescues this defect.