D6 and the atypical chemokine receptor family: Novel regulators of immune and inflammatory processes

Chemokines are key regulators of leukocyte migration and play important roles in a number of physiological and pathological immune and inflammatory contexts. In addition to the classical signalling chemokine receptors there has emerged, recently, a new subclass of atypical chemokine receptors. This subfamily is characterised by an apparent lack of signalling and, in some cases, by an ability to internalise and degrade chemokine ligands. This review describes the family of atypical chemokine receptors with particular emphasis on the D6 receptor. The in vitro and in vivo biology of D6 is described, which indicates that D6 is active as a scavenger of inflammatory CC-chemokines and appears to play essential roles in the regulation of inflammatory responses.