Interleukin 27 EBI3 (IL-27 EI3) predicts a molecular mass of 23.4 kDa. IL-27 is a heterodimeric cytokine that is encoded by Epstein-Barr virus-induced gene 3 (EBI3) and IL-27p28. It is expressed by antigen presenting cells and interacts with a specific cell-surface receptor complex known as IL-27 receptor (IL-27R).