elevated il-17 and tgf-β serum levels: a positive correlation between t-helper 17 cell-related pro-inflammatory responses with major depressive disorder

Introduction: depression is a mental disorder that highly associated with immune system. therefore, this study compares the serum concentrations of il-21, il-17, and transforming growth factor β (tgf-β) between patients with major depressive disorder and healthy controls.methods: blood samples were collected from 41 patients with major depressive disorder and 40 healthy age-matched controls with no history of malignancies or autoimmune disorders. the subjects were interviewed face to face according to dsm-iv diagnostic criteria. depression score was measured using completed beck depression inventory in both groups. the serum concentrations of il-21, il-17, and tgf-β were assessed using elisa.results: the mean score of beck depression score in the patient and control groups was 35.4±5.5 and 11.1±2.3. il-17 serum concentrations in the patients and the control group were 10.03±0.6 and 7.6±0.6 pg/ml, respectively (p=0.0002). tgf-β level in the patients group was significantly higher than compare to the control group; 336.7±20.19 vs. 174.8±27.20 pg/ml, (p<0.0001). however, the level of il-21 was not statistically different between the two groups 84.30±4.57 vs. 84.12±4.15 pg/ml (p>0.05).conclusion: considering pro-inflammatory cytokines, current results support the associationof inflammatory response and depressive disorder. so, it seems that pro-inflammatory factors profile can be used as indicator in following of depression progress and its treatment impacts.