European isolation and confinement study. Confinement and immune function.

During spaceflight, several unusual factors act on the physiology of the astronaut: weightlessness, radiation, confinement, isolation, living and working in a small group, workload, and anxiety. The resulting physiological changes are known to include alterations of the immune system. It is difficult to determine from observations on astronauts which space-related factor(s) are responsible for the immune changes. Studies of analogous environments on Earth have supplied only scarce information. Dedicated simulation studies provide a better tool, where some space-related stress factors (weightlessness, radiation) are absent, but others are or can be present: isolation and confinement, small group living, workload, and anxiety. A reduction in immune activity was found in bed rest studies and in long-term Soviet confinement experiments (after 90 days). In the ISEMSI confinement experiment (28 days), a tendency to immune activation (PHA-reactivity and interleukin-2 production) was observed in two out of six subjects. There is a need for further experiments, in which a large number of immunological parameters can be analyzed.