Exogenous Amino Acids Are Essential for Interleukin-7 Induced CD8 T Cell Gowth

IL-7 signalling is important in regulating both survival and cellular size (growth) of T cells. While glucose metabolism has previously been implicated in the mechanism of IL-7 induced survival and growth, the role of amino acids has not before been reported. Here, we show IL-7 dependent T cell survival does not require either exogenous glucose or amino acids. In contrast, maintenance of cell size and IL-7 induced growth were specifically dependent on amino acids. Furthermore, cellular amino acid uptake was implicated in the mechanism of IL-7 induced growth. Analysis of IL-7 regulated gene expression revealed that neutral and cationic amino acid transporters were specific transcriptional targets of IL-7 signalling. In contrast, none of the four glucose transporters expressed in T cells were modulated. Taken together, these data reveal for the first time the central importance of amino acid homeostasis for IL-7 regulated T cell growth.