Dendritic cell chemotaxis and transendothelial migration are induced by distinct chemokines and are regulated on maturation

The capacity of dendritic cells (DC) to initiate immune responses is dependent on their specialized migratory and tissue homing properties. Chemotaxis and transendothelial migration (TEM) of DC were studied in vitro. Immature DC were generated by culture of human monocytes in granulocyte‐macrophage colony‐stimulating factor and IL‐4. These cells exhibited potent chemotaxis and TEM responses to the CC chemokines macrophage inflammatory protein (MIP)‐1α, MIP‐1β, RANTES, and monocyte chemotactic protein‐3, and weak responses to the CC chemokine MIP‐3β and the CXC chemokine stromal cell‐derived factor (SDF)‐1α. Maturation of DC induced by culture in lipopolysaccharide, TNF‐α or IL‐1β reduced or abolished responses to the former CC chemokines but markedly enhanced responses to MIP‐3β and SDF‐1α. This correlated with changes in chemokine receptor expression: CCR5 expression was reduced while CXCR4 expression was enhanced. These findings suggest two stages for regulation of DC migration in which one set of chemokines may regulate recruitment into or within tissues, and another egress from the tissues.