Abstract: Abstract: There has been increasing interest in the putative involvement of the immune system in mental disorders. Depression is suggested to be caused by the immune dysfunction. Psychological and physiological stress can activate immune function, resulting in production of cytokines which exert effects on metabolism of neurotrasmitters, neuroendocrine function, and the neuron plasticity. Although most cytokines are secreted by the immune cells, recent data demonstrate that astrocytes and/or microglia, even neurons, can also produce cytokines. "Cytokine hypothesis of depression", which proposes that cytokines play an important role in depressive disorder, provide a new perspective in the study of depression pathogenesis and the new treatment approach of Psychoneuroimmunology for the clinical depression therapy

Key words: Psychoneuroimmunology, depression, cytokines