Interleukin 27 (IL-27), a member of the IL-12 family, is a heterodimeric protein consisting of two subunits: Epstein-Barr virus (EBV)-induced gene 3 (EBI3) (also known as IL-27B) and IL-27 p28 (known as IL-30). IL-27 is produced by antigen-presenting cells and plays an important function in regulating the activity of B- and T-lymphocytes. The effects of IL-27 are eliciting by its interaction with a specific cell-surface receptor complex composed of two proteins known as IL-27R and gp130.
IL-27 has both pro- and anti-inflammatory properties. In response to infection, IL-27 induces monocytes and mast cells to secrete pro-inflammatory cytokines. It induces naive CD4 T cells to proliferate and develop Th1 cell responses. IL-27 also promotes effector functions of NK cells and CD8 T cells. As an anti-inflammatory immunomodulator, IL-27 has been found to have the ability to inhibit Th1 or Th2 responses and restrict the strength and duration of adaptive immune responses. Recent studies indicate that IL-27 has potent anti-tumor activity. It has been reported that IL-27 is critically involved in the induction of inflammation in rheumatoid arthritis.