Differential pattern of cytokine production by depressed medical students; evidence for involvement of cytokine network in pathology of depression.

BACKGROUND Previous studies revealed that the immune responses of depressed patients can be affected by alteration of immune system factors; however, the immune genes mainly influenced are yet to be fully understood. Therefore, the main aim of present study was to identify serum levels of drastic inflammatory cytokines including IL-17A, IL-12, and IL-6 as well as anti-inflammatory cytokines, IL-10 and TGF-beta, amongst Iranian depressed medical students. METHODS Peripheral blood specimens were collected from 38 Iranian medical student patients with moderate and severe depression along with 43 healthy students as control subjects. The serum levels of IL-17A, IL-12, IL-6, IL-10, and TGF-beta were assessed using the ELISA technique. RESULTS Our results showed that the serum IL-10 level was significantly (p = 0.011) decreased in depressed patients (2.8 +/- 0.41 pg/mL) compared to healthy controls (4.3 +/- 0.4 pg/mL). The results also revealed that serum levels of TGF-beta were significantly increased in severely (12.75 +/- 5.22) compared to moderately (5.3 +/- 0.7) depressed patients (p = 0.045). CONCLUSIONS According to the results of the present study, the decreased IL-10 level in the depressed patients may be responsible for the induction of inflammation in Iranian depressed patients. Additionally, increased serum levels of TGF-beta in severely compared to moderately depressed patients may be related to normal immune responses against inflammation in severely depressed patients.