Interleukin 35

Interleukin 35 (IL-35) is an IL-12 family cytokine that is produced by regulatory, but not effector, T cells and plays a role in immune suppression. It is a dimeric protein composed of IL-12α and IL-27β chains, which are encoded by two separate genes called IL12A and EBI3, respectively. Secreted by regulatory T cells (Tregs), IL-35 suppresses inflammatory responses of immune cells. Studies in mice show the absence of either IL-35 chain from regulatory Tregs reduces the cells' ability to suppress inflammation; this has been observed during cell culture experiments and using an experimental model for inflammatory bowel disease. To produce its suppressive effects, IL-35 has selective activities on different T cell subsets; it induces proliferation of Treg cell populations but reduces activity of Th17 cell populations.