THE ROLE OF PSYCHONEUROENDOCRINE FACTORS ON SPACEFLIGHT-INDUCED IMMUNOLOGICAL ALTERATIONS

This paper summarizes previous in-flight infections and novel conditio ns of spaceflight that may suppress immune function. Granulocytosis, m onocytosis, and lymphopenia are routinely observed following short dur ation orbital flights. Subtle changes within the monocyte and T cell p opulations can also be noted by flow cytometric analysis. The similari ty between the immunological changes observed after spaceflight and ot her diverse environmental stressors suggest that most of these alterat ions may be neuroendocrine-mediated. Available data support the hypoth esis that spaceflight and other environmental stressors modulate norma l immune regulation via stress hormones, other than exclusively glucoc orticoids. It will be essential to simultaneously collect in-flight en docrine, immunologic, and infectious illness data to determine the cli nical significance of these results. Additional research that delineat es the neuroendocrine mechanisms of stress-induced changes in normal i mmune regulation will allow clinicians in the future to initiate proph ylactic immunomodulator therapy to restore immune competence altered b y the stress of long-duration spaceflight and therefore reduce morbidi ty from infectious illness, autoimmune disease, or malignancy.