Expression of Interleukin-12-Related Cytokine Transcripts in Inflammatory Bowel Disease: Elevated Interleukin-23p19 and Interleukin-27p28 in Crohnʼs Disease But Not in Ulcerative Colitis

BackgroundIt has been suggested that Crohn's disease (CD) is associated with an exaggerated T-helper 1 cytokine response manifested by increased production of interleukin (IL)-12. IL-12 is a heterodimeric protein comprising 2 disulfide-linked subunits designated p35 and p40. Recently, IL-12-related cytokines, IL-23 and IL-27, were described. Biologically active IL-23 is a heterodimer whose p40 subunit is identical to IL-12p40 whereas its p19 subunit is distantly related to IL-12p35. IL-27 consists of EBI3, an IL-12p40-related protein, and p28, a newly discovered IL-12p35-related polypeptide.