Tether before synapse

Chemokines are captured on the surface of dendritic cells in lymph nodes, and they in turn capture T cells, say Rachel Friedman, Jordan Jacobelli, and Matthew Krummel (University of California, San Francisco, CA). The tethered T cells continue to search for a site worthy of a full immunological synapse, which they can form with either the same or another antigen-presenting cell (APC).

Chemokines were known to costimulate T cell activation in vitro and up-regulate integrins that might slow down the T cells. But chemokines in solution also induced T cell migration past a surface laden with stimulatory T cell receptors (TCRs).

This “paradox,” says Krummel, is resolved by the new data. He thinks the T cells bind APCs and then move arm over arm, “like swinging...