CD8A and infection: Memory CD8+ T cells exhibit an “open” epigenetic signature at the Gcnt1 promoter and IL-15 (and potentially other cytokines that activate the STAT5 transcription factor) is sufficient to stimulate core 2 O-glycan synthesis, thereby allowing circulating memory CD8+ T cells to traffic into a site of infection without needing to be reactivated by professional antigen-presenting cells.