Levels of serum interleukin (IL)-6, IL-1beta, tumour necrosis factor-alpha and leptin and their correlation in depression

Objective: To investigate the relationship between leptin and cytokines in depressed patients. Methods: Thirty-three unmedicated patients (24 female, nine male) with depressive disorder and 23 healthy controls (16 female, seven male) were assessed for serum levels of interleukin (IL)-6, IL-1β, tumour necrosis factor-α (TNF-α) and leptin. Results: Levels of IL-6 and TNF-α in depressed patients were higher than in normal controls. There were significantly lower leptin levels in depressed patients than in normal controls. There were also significant differences in the leptin levels, being higher in female than in male patients, and in female than in male controls. Conclusions: IL-6 and TNF-α cytokines and leptin are important in the psychoimmunology of depressed patients. There were gender differences in leptin levels in depression.