Control of dendritic cell migration by chemokines

Dendritic cells (DC) are antigen presenting cells able to activate naive T lymphocytes. Immature DC are highly motile and efficiently take up and process antigens. Immature DC localise in non-lymphoid organs where they exert a sentinel function. Upon exposure to immune or inflammatory signals DC undergo maturation and migrate to T cell areas of lymphoid organs. Thus, the correct functioning of DC involves localisation in tissues and trafficking via the lymph or blood to lymphoid organs. Chemokines have emerged as important regulators of DC migration. DC express receptors for and respond to a set of chemoattractants which overlaps with, but is distinct from, that active on other leukocytes. Functional maturation is associated with loss of responsiveness to chemokines present at sites of inflammation and acquisition of a receptor repertoire which renders these cells responsive to signals which guide their localisation in lymphoid organs. A better understanding of the molecular basis of DC trafficking may provide molecular and conceptual tools to direct and modulate DC traffic as a strategy to up-regulate and orient specific immunity.