Chemokine receptor distribution on the surface of repolarizing T cells.

T cells migrate constitutively with a polarized morphology, underpinned by signaling compartmentalization and discrete cytoskeletal organizations, giving rise to a dynamic and expansive leading edge, distinct from the stable and constricted uropod at the rear. In vivo, the motion and function of T cells at various stages of differentiation is highly directed by chemokine gradients. When cognate ligands bind chemokine receptors on their surface, T cells respond by reorientating their polarity axis and migrating toward the source of the chemokine signal. Despite the significance of such chemotactic repolarization to the accurate navigation and function of T cells, the precise signaling mechanisms that underlie it remain elusive. Notably, it remained unclear whether the distribution of chemokine receptors on the T cell surface is altered during repolarization. Here, we developed parallel cell-secreted and microfluidics-based chemokine gradient delivery methods and employed both fixed imaging and live lattice light-sheet microscopy to investigate the dynamics of chemokine receptor CCR5 on the surface of primary murine CD8