en Cellular and molecular Neuroscience Cellular and molecular Neuroscience Original Original <p dir="ltr" style="text-align: justify;"><strong>Introduction:</strong> Depression is a mental disorder that highly associated with immune system.&nbsp;Therefore, this study compares the serum concentrations of IL-21, IL-17, and transforming&nbsp;growth factor &beta; (TGF-&beta;) between patients with major depressive disorder and healthy controls.<br> <strong>Methods:</strong> Blood samples were collected from 41 patients with major depressive disorder and&nbsp;40 healthy age-matched controls with no history of malignancies or autoimmune disorders. The&nbsp;subjects were interviewed face to face according to DSM-IV diagnostic criteria. Depression&nbsp;score was measured using completed Beck Depression Inventory in both groups. The serum&nbsp;concentrations of IL-21, IL-17, and TGF-&beta; were assessed using ELISA.<br> <strong>Results:</strong> The mean score of Beck Depression score in the patient and control groups was&nbsp;35.4&plusmn;5.5 and 11.1&plusmn;2.3. IL-17 serum concentrations in the patients and the control group were&nbsp;10.03&plusmn;0.6 and 7.6&plusmn;0.6 pg/mL, respectively (P=0.0002). TGF-&beta; level in the patients group was&nbsp;significantly higher than compare to the control group; 336.7&plusmn;20.19 vs. 174.8&plusmn;27.20 pg/mL,&nbsp;(P<0.0001). However, the level of IL-21 was not statistically different between the two groups&nbsp;84.30&plusmn;4.57 vs. 84.12&plusmn;4.15 pg/mL (P>0.05).<br> <strong>Conclusion:</strong> Considering pro-inflammatory cytokines, current results support the associationof inflammatory response and depressive disorder. So, it seems that pro-inflammatory factors&nbsp;profile can be used as indicator in following of depression progress and its treatment impacts.</p> Major depressive disorder, Interleukin-17, interleukin-21, Transforming growth factor-beta, Inflammatory response 137 142 http://bcn.iums.ac.ir/browse.php?a_code=A-10-776-1&slc_lang=en&sid=1 Mohammad Hasan Davami davamimh@gmail.com 1370031947532846007443 1370031947532846007443 No Department of Immunology and Microbiology, School of Medicin, Jahrom University of Medical Sciences, Jahrom, Iran. Rasoul Baharlou Baharlour@gmail.com 1370031947532846007444 1370031947532846007444 Yes Department of Immunology and Microbiology, School of Medicin, Jahrom University of Medical Sciences, Jahrom, Iran. Abbas Ahmadi Vasmehjani a.vasmehjani23@yahoo.com 1370031947532846007445 1370031947532846007445 No Department of Immunology and Microbiology, School of Medicin, Jahrom University of Medical Sciences, Jahrom, Iran. Ahmad Ghanizadeh ghanizad@tums.ac.ir 1370031947532846007446 1370031947532846007446 No Department of Psychiatry, School of Medicin, Shiraz University of Medical Sciences, Shiraz, Iran. Mitra Keshtkar baharlour@hotmail.com 1370031947532846007447 1370031947532846007447 No Department of Psychiatry, School of Medicin, Jahrom University of Medical Sciences, Jahrom, Iran. Iman Dezhkam i.dezhkam@gmail.com 1370031947532846007448 1370031947532846007448 No Department of Student Research Committee, School of Medicine, Jahrom University of Medical Sciences, Jahrom, Iran. Mohammad Reza Atashzar mr.atashzar@yahoo.com 1370031947532846007449 1370031947532846007449 No Department of Student Research Committee, School of Medicine, Jahrom University of Medical Sciences, Jahrom, Iran.