DCs redirect T cell traffic

Dendritic cells (DCs) are the master regulators of T cell recirculation, according to a study by Mora et al. on page 303. Memory T cells—thought to be programmed to return to the location in which they first encountered antigen—can be rerouted by an encounter with a DC from another location.Previous studies have shown that memory T cells express a characteristic array of adhesion molecules and chemokine receptors on their surface that reflect the location of activation and direct their trafficking back to that site. Recently, this group showed that gut DCs, but not spleen or peripheral lymph node DCs, induced the up-regulation of the gut-homing integrin α4β7 on T cells.

Mora et al. now show that these “committed” T cells are not set in their ways. In...