Epstein-Barr Virus Induced Gene-3 (EBI3), is a secreted glycoProtein belonging to the hematopoietin receptor family and is related to the p40 subunit of IL-12. EBI3 was identified by its induced expression in B-lymphocytes in response to EpsteinBarr virus infection. EBI3 forms heterodimers with p28 to form IL-27 and with p35 to form IL-35. Both IL-27 and IL-35 have Anti-and regulatory activity. Recombinant EBI3 is a non-glycosylated Protein, containing 209 amino acids, with a molecular weight of 23.3 kDa.