Stress effects on immunity and its application to clinical immunology.

Various stressors, including both psychological as well as physiological, have been demonstrated to influence the immune response, presumably through activation of the hypothalamic-pituitary-adrenal axis and sympathetic nervous system. Anecdotal evidence, and retrospective and prospective studies, have demonstrated an effect of psychological and physiological stress on immune-based diseases such as asthma, atopy and infections. Alterations in immune function, in particular the type-1/type-2 cytokine balance, secondary to increased psychological stress, are thought to mediate these changes in health. The field of psychoneuroimmunology seeks to establish the link between behaviour, neuroendocrine functions, immune responses and health. The current review will describe the effect of psychological stress on immune function, the impact of psychological stress on immune-based pathology, and the future directions of research to determine the mechanisms and clinical significance of the field of psychoneuroimmunology.