TFRC and influenza: As mentioned above, IL-2 treatment of grafted mice reduced rather than enhanced the generation of Tfr and Tfh cells, which is in line with the decreased formation of these two subsets seen in mice injected with soluble IL-2 during influenza infection [39] and the direct depletion of autoreactive Tfh cells via low-dose IL-2 in an autoimmune model [40].