Extracellular ATP released by T cells exerts pleiotropic effects in an autocrine manner. In The EMBO Journal, Viola and colleagues demonstrate that paracrine ATP can also influence the motility of T cells. Activation of isolated T cells or T cells in lymph node slices via the T cell antigen receptor (TCR) shows that neighboring T cells also achieve calcium flux even without triggering via the TCR. This paracrine action is mediated by the release of ATP from the stimulated T cells, which activates the purinergic receptors P2X4 and P2X7 on bystander T cells. The calcium flux in these ATP-sensing cells results in lower motility. This ability of cells triggered via the TCR to influence the activity of bystander cells might enhance the swarming and antigen-scanning ativity of T cells in lymph nodes.

EMBO J. (19 May 2014) doi:10.15252/embj.201386666