Interleukin 27 (IL27) is a heterodimeric cytokine belonging to the IL-12 family that is composed of two subunits; Epstein-Barr virus (EBV)-induced gene 3 (EBI3) (also known as IL-27B) and IL27-p28 (known as IL-30). IL-27 is produced by  antigen-presenting cells. 
IL-27 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  IL27R and gp130. 
References [ edit ]
^ Larousserie, F; Bardel, E; Pflanz, S; Arnulf, B; Lome-Maldonado, C; Hermine, O; Brégeaud, L; Perennec, M; et al. (April 2005). "Analysis of interleukin-27 (EBI3/p28) expression in Epstein-Barr virus- and human T-cell leukemia virus type 1-associated lymphomas: heterogeneous expression of EBI3 subunit by tumoral cells". The American Journal of Pathology 166 (4): 1217–28. doi: 10.1016/S0002-9440(10)62340-1. PMC 1602381. PMID 15793300.
^ Lucas S, Ghilardi N, Li J, de Sauvage FJ (December 2003). "IL-27 regulates IL-12 responsiveness of naive CD4+ T cells through Stat1-dependent and -independent mechanisms". Proceedings of the National Academy of Sciences of the United States of America 100 (25): 15047–52. doi: 10.1073/pnas.2536517100. PMC 299900. PMID 14657353.
^ Larousserie F, Charlot P, Bardel E, Froger J, Kastelein RA, Devergne O (May 2006). "Differential effects of IL-27 on human B cell subsets". Journal of Immunology (Baltimore, Md. : 1950) 176 (10): 5890–7. doi: 10.4049/jimmunol.176.10.5890. PMID 16670296.
^ Pflanz S, Hibbert L, Mattson J, Rosales R, Vaisberg E, Bazan JF, Phillips JH, McClanahan TK, de Waal Malefyt R, Kastelein RA (February 2004). "WSX-1 and glycoprotein 130 constitute a signal-transducing receptor for IL-27". Journal of immunology (Baltimore, Md. : 1950) 172 (4): 2225–31. doi: 10.4049/jimmunol.172.4.2225. PMID 14764690.