[Psyche and immunity. A selected literature study of psychoneuroimmunology in healthy persons].

In the new field of psychoneuroimmunology essential ground has already been broken. Precisely in man, however, only hypotheses are possible in important areas: one that is commonly voiced is that stress weakens the immune system and would favour the onset of disease. A situation report is presented which summarizes, classifies and compares all 67 published studies relating psychic influences to immunologic factors in healthy human beings. A notable proportion turned out to be doubtful from the formal standpoint, e.g. no controls (40 publications) or with fewer than 30 probands (19). In 13 of these studies neuroendocrinologic parameters were taken into account and in 14 biological (health/disease) parameters. 42 studies were based on "externally defined" stress situations (partner loss, examinations, care of severely ill family members, space shuttle mission, etc.), 16 on specific personality traits and 9 on experimental stress situations or relaxation efforts. Since the studies varied widely in design, psychic starting position, psychic assessment (91 different methods) and immunity (68 varying parameters) and also in regard to the biological result (various "endpoints" of health/disease), only a few general conclusions can be drawn. Subjective or objective stress can be associated with diminished lymphocyte functions such as reduced mitogen stimulation and natural killer cell activity, elevated antibody titers against some latent and/or ubiquitous viruses, and reduced immunoglobulin A in saliva. This is confirmed to varying degrees, usually on a shortterm basis and not in all studies. Others contain evidence that the immunologic changes mentioned may be associated with particular personality traits (anxiety, depression, loneliness, good coping, power motive syndrome, social support, etc.). What the immunologic changes had in common was that they moved within a relatively narrow range and overstepped the norm little or only marginally. Whether the immunologic "anomalies" observed reflect a weakened immune system or an adequate "homeostatic" immune modulation by psychic signals, or point to adequate immune defence in an altered "antigen situation" arising from a changed lifestyle in stress situations, cannot be said. There is little evidence of a relationship to disease onset. While the present review shows certain relationships between psychic and immunologic factors, their biological relevance remains unclear. The often voiced hypothesis that stress weakens the immune system and a larger number of diseases therefore ensue cannot be confirmed or denied by the available data. The results permit other, contradictory hypotheses.