Significance of serum Il-9 levels in inflammatory bowel disease

IL-9, which may be an inflammatory or regulatory cytokine, can be experimentally produced in a Th17 or modified Th2 context in the presence of T cell receptor (TCR) stimulation. The primary aim of this study was to measure serum IL-9 levels in patients with inflammatory bowel disease (IBD), and evaluate their relationships with the patients' clinical characteristics. The secondary aim was to determine the levels of interferon-3 (IFN (interferon)-3), Th2 cytokines (IL-4, IL-5 and IL-13), and IL-6 in order to clarify the context of detectable peripheral cytokines in which IL-9 is produced. Venous blood samples of 43 IBD patients (20 with Crohn's disease [CD] and 23 with ulcerative colitis [UC]) were analysed by means of quantitative enzyme-linked immunosorbent assays using purified anti-human IL-4, IL-5, IL-13, IFN-3, IL-9 and IL-6 antibodies, and the laboratory findings were statistically correlated with their clinical expression. None of the patients showed the peripheral presence of IL-4, IL-5 and IL-13. Forty (93%) were positive for IFN-3, thus confirming the presence of Th1 in both UC and CD, and IFN-3 levels correlated with disease activity (P = 0.045). Eighteen patients (41%) were positive for IL-9, which was associated with a severe prognosis (P