A cytokine’s secrets revealed

Interleukin-35 (IL-35) - a protein secreted by certain T cells - has important immunosuppressive properties and how it achieves these effects is reported online in Nature Immunology this week.Dario Vignali and colleagues determine the receptor for IL-35 and show it to be composed of a novel combination of known receptor components. Engagement of this receptor triggers a unique sequence of downstream signaling molecules which are responsible for suppressing target cells and - if the target is a T cell - converting it into another IL-35-expressing cell which is in its turn suppressive.This study highlights how the immune system can use modular receptor and cytokine components in different combinations to elicit distinct functional consequences.