Objectives. To analyze the relationship between depression and the immune system disorders that mediate an increased activity of the hypothalamic-pituitary-adrenal axis (HPA).
Review. In the 1980s the relation between depression and cell-mediated response impairment (i.e. a reduced absolute number of TandB lymphocytes, and diminished number and hypoactivity of NK cells) was described in many studies. In the 1990s reports were published concerning the effect of HPA axis disturbances on the pathogenesis of depression, as well as the association of depressive disorders with an increased level of proinflammatory cytokines in patients in whom the concurrence of depression and an inflammatory process had been excluded.
Conclusion. In the 20th century a significant progress was made in the understanding of mechanisms underlying the immune and endocrine system dysfunctions in the pathogenesis of recurrent depressive disorders. A number of stressful stimuli can lead to an increase in the levels of proinflammatory cytokines such as IL-1, IL-6 or TNF- a produced in the peripheral and central nervous system. The increased cytokine concentration in the c.n.s. results in an increased activity of the HPA axis and in consequence, in an increased concentration of corticoliberin and glucocorticosteroids. The latter can evoke and exacerbate the symptoms characteristic of depressive disorders.