Research Article Serum Interleukin 17 Levels in Patients with Crohn’s Disease: Real Life Data Abdurrahman Sahin, 1 Turan Calhan, 2 Mustafa Cengiz, 3 Resul Kahraman, 4 Kubra Aydin, 5 Kamil Ozdil, 6 May Korachi, 5 and H. Mehmet Sokmen 6 1 Department of Gastroenterology, Elazig Education and Research Hospital, Rizaiye Mah. Inonu Caddesi, 23200 Elazig, Turkey 2 Gastroenterology Department, Turkiye Gazetesi Hospital, 34381 Istanbul, Turkey 3 Department of Gastroenterology, Ankara Oncology Education and Research Hospital, 06500 Ankara, Turkey 4 Department of Gastroenterology, Batman State Hospital, 72070 Batman, Turkey 5 Department of Genetics and Bioengineering, Yeditepe University, 34755 Istanbul, Turkey 6 Department of Gastroenterology, Umraniye Training and Research Hospital, 34764 Istanbul, Turkey Correspondence should be addressed to Abdurrahman Sahin; arahmansmd@yahoo.com Received 3 June 2014; Accepted 16 June 2014; Published 16 July 2014 Academic Editor: Giuseppe Murdaca Copyright © 2014 Abdurrahman Sahin et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Te aim of this study was to investigate serum IL17 levels in patients with Crohn’s disease (CD) and to investigate the relationship between serum IL17 levels with disease activity. Methods. Fify patients with CD and sex- and age-matched 40 healthy controls were included in the study. Te serum IL17 levels, complete blood count, blood chemistry, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) levels were measured, and Crohn’s disease activity was calculated using Crohn’s disease activity index (CDAI). Results. Te mean serum IL17 level of CD patients did not difer from those of healthy controls ( > 0.05). Tere was no diference between the mean serum IL levels of active CD patients and of quiescent CD patients ( > 0.05). However, the mean IL17 level of active patients was lower than of control subjects ( = 0.02). Serum IL17 was not correlated with infammatory markers (ESR, CRP, white blood count, platelet count, and albumin) and CDAI. Conclusions. Peripheral blood serum IL17 levels of CD patients were not higher than of healthy controls, and also, serum IL17 level was not correlated with clinical disease activity. Peripheral IL17 measurement is not a useful tool for detecting and monitoring Crohn’s disease which is understood to have complex etiopathogenesis. 1. Introduction Crohn’s disease (CD) is a chronic relapsing infammatory disease afecting the gastrointestinal tract and presenting with extraintestinal manifestations as well. Although the etiopathogenesis of this disease is not completely understood, it seems to be infuenced by several environmental factors in genetically predisposed individuals [1, 2]. T helper lympho- cytes (T) play an important role in the pathogenesis of CD. Crohn’s disease is postulated to be an infammatory disease mediated by T1 cells and recently also by T17 cells [3]. T17 cells are major contributors to several autoimmune diseases that were previously thought to be T1 cell predom- inant diseases. Tese autoimmune diseases can be listed as rheumatoid arthritis, psoriasis, systemic lupus, scleroderma, multiple sclerosis, infammatory bowel disease, autoimmune myocarditis, and endometriosis [4]. T17 cells also play an important role in maintaining intestinal mucosal barrier function by afecting innate and adaptive responses. Mucosal T17 cells prevent migration of pathogens from breaking mucosa to the systemic circulation through the chemotaxis of neutrophils and macrophages. One of the important features of T17 cells is to bal- ance mucosal infammation by regulating the immunogenic response against self-antigens or intestinal pathogens due to their relationship with regulatory T cells. Te other is plasticity, the ability of these cells to diferentiate to other T cell subgroups under various types of stimulation. T17 Hindawi Publishing Corporation Disease Markers Volume 2014, Article ID 690853, 6 pages http://dx.doi.org/10.1155/2014/690853