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Publisher Summary This chapter discusses alterations in immune responses during and after spaceflight for humans as well as for animals. The observed changes include: reduced PHA-stimulated T lymphocyte proliferation, decreased Natural Killer cell cytotoxicity, and in vivo depressed delayed cutaneous hypersensitivity. The decrease in immune responses might be a consequence of hyperoxygenation during extravehicular activities, environmental stressors or an indirect effect of microgravity on various body systems. The physiological adaptations of the body to the space environment, and especially to microgravity, have been investigated for the cardiovascular, skeletal, muscle, and immunohematological systems. The fluid shift induced by microgravity in the early days of flight leads to certain hormonal changes, such as a decreased release of the atrial natriuretic factor by the heart. The fluid shift probably leads to increased diuresis, loss of electrolytes, and in turn, a reduction in plasma volume. |
