Sphingosine 1-phosphate as a novel immune regulator of dendritic cells.

Although originally described as an intracellular second messenger, sphingosine 1-phosphate (S1P) has recently been shown to be involved in several physiological and pathological functions as an extracellular mediator. S1P receptors are widely expressed and thought to regulate important functions in cell signalling. Recently, the role of S1P on the immune system has evoked great interest. In particular, several aspects of the effects on antigen-presenting cells (APCs) as dendritic cells (DC) in mice and humans have been reported. In this review, we focus on the role played by S1P on the DC system and its effects in immune-related pathological states.