Interleukin 27 (IL-27) is a member of the IL-12 cytokine family. It is a heterodimeric cytokine that is composed of two distinct genes, Epstein-Barr virus-induced gene 3 (EBI3) and IL-27p28. IL-27 is expressed by antigen presenting cells and interacts with a specific cell-surface receptor complex known as IL-27 receptor (IL-27R). This receptor consists of two proteins, IL-27? and gp130. IL-27 induces differentiation of the diverse populations of T cells in the immune system and also upregulates IL-10.