Dendritic Cell Migration: An Essential Step in Initiating Adaptive Immunity Across Tissues.

Immune surveillance of tissues is primarily carried out by dendritic cells (DCs), which act as sentinels for the adaptive immune system. To accomplish this task, DCs migrate from tissues to regional lymph nodes, or from blood-exposed regions of the spleen to the white pulp, to prime T cell responses. DC migration is a tightly regulated process that occurs at both steady state and during inflammation, and is dependent on sensing a wide array of chemoattractant molecules. Migration involves dynamic cytoskeletal rearrangement after signaling from chemotactic receptors, followed by rapid chemotaxis to specific regions of lymphoid tissues along gradients of chemoattractant molecules. In this review, we explore how DCs regulate the process of migration at the level of activation and receptor expression, chemoattractant sensing, and signaling to induce cytoskeletal rearrangement. We discuss differences in how DC subsets migrate, including the different regions these subsets localize to within lymphoid tissues and how these differences impact T cell responses. We also examine DC migration in the context of diverse tissue environments, with a focus on barrier sites. This comparison contributes to a holistic understanding of the common ways DC migration is regulated, as well as key differences that contribute to divergent adaptive immune responses.