Isolation and confinement as a model for spaceflight immune changes.

The immune system of astronauts is disturbed during and after spaceflight. This situation may result from stressors encountered during the flight (microgravity, radiation, psychological stress, or confinement) or from physiological changes (demineralization or fluid shift). Therefore, ground-based investigations should be designed to determine the effects of these factors on the immune system. Very little is known about the influence of confinement or isolation on immune reactions. However, interesting data exist from experiments with animals and humans under different conditions (submarines, antarctic expeditions, single-person cave isolation, and underwater diving). The question remains as to whether these results can be extrapolated to spaceflight. Therefore, investigations of humans under isolation conditions analogous to space missions have been performed by Russian and, more recently, European investigators. Such investigations are important for understanding the physiological and psychological disturbances that occur during long periods of confinement, especially when future lunar and martian missions are considered.