Chemokines on the move: control by the chemokine "interceptors" Duffy blood group antigen and D6.

Chemokines drive and direct leukocyte trafficking across the biological barriers. Controlling the microanatomical localization and quantity of chemokines is of fundamental importance in regulating these migratory responses. Here we discuss the emerging roles that two atypical chemokine receptors, Duffy antigen and D6, may play in controlling chemokine movement and how this may impinge on chemokine function. Mechanistically, Duffy antigen and D6 represent a subclass of chemokine internalizing receptors, "interceptors," taking chemokines into nucleated cells in the apparent absence of signaling. The subsequent fate of chemokines, either transport or degradation, may ultimately depend on cell type-specific targeting within the endocytotic pathway.