[Stress-induced immune changes, and brain-immune interaction]

It is commonly known that psychosocial stress influences the immune system. Recent progress in neuroscience and immunology has elucidated the mechanism of stress induced immune changes, as well as brain-immune interactions. Numerous studies suggest that psychosocial stress increases the susceptibility to bacterial and viral infections. Stressful life events, inappropriate coping behavior and disturbed emotional states are associated with decreased phagocytosis, reduced lymphocyte response to mitogen, diminished natural killer cell activity, and with the risk of developing neoplasm. There is increasing evidence for a bidirectional communication system between the immune system and the brain through common receptors and biologically active substances such as cytokines and neuropeptides. Research has demonstrated the direct regulatory effect of the autonomic nervous system on the immune system, as well as the hypothalamic-pituitary-adrenal axis. It has also been shown that immune and allergic reactions can be classically conditioned, cytokines have an effect on the central nervous system, and that lymphocytes can produce neuropeptides. In this article, stress induced immune changes and brain-immune interactions are reviewed and discussed using pertinent literature, including studies by the authors.