EFFECT OF SPACE-FLIGHT ON CYTOKINE PRODUCTION

Space flight has been shown to alter many immunological responses. Amo ng those affected are the production of cytokines, Cytokines are the m essengers of the immune system that facilitate communication among cel ls that allow the interaction among cells leading to the development o f immune responses. Included among the cytokines are the interferons, interleukins, and colony stimulating factors. Cytokines also facilitat e communication between the immune system and other body systems, such as the neuroendocrine and musculoskeletal systems. Some cytokines als o have direct protective effects on the host, such as interferon, whic h can inhibit the replication of viruses. Studies in both humans and a nimals indicate that models of space flight as well as actual space fl ight alter the production and action of cytokines. Included among thes e changes are altered interferon production, altered responsiveness of bone marrow cells to granulocyte/monocyte-colony stimulating factor, but no alteration in the production of interleukin-3. This suggests th at there are selective effects of space flight on immune responses, i. e. not all cytokines are affected in the same fashion by space flight. Tissue culture studies also suggest that there may be direct effects of space flight on the cells responsible for cytokine production and a ction. The results of the above study indicate that the effects of spa ce flight on cytokines may be a fundamental mechanism by which space f light not only affects immune responses, but also other biological sys tems of the human.