CD44 and influenza: In our experiment, mice receiving IL-2 treatment showed an increased frequency of effector CD8+ T cells, characterized by both effector memory (CD44+CD62L-) as well as short-lived effector (KLRG1+CD127-) phenotypes in influenza infection, together with the increased production of granzymes and IFN-γ (Fig 2D, 2F, 2H and 2I).