Lymphocyte reactivity during spaceflight.

Over twenty years of spaceflight have demonstrated that man can easily survive and work in weightless conditions. However, a number of physiological changes may affect crew performance in space. Besides the well known disturbances of the vestibular and cardiovascular systems, bone demineralization, and decrease of erthrocyte mass, certain immunological alterations have been observed in space crews after flight. One of them--the reduction of lymphocyte reactivity to mitogens--was the subject of our investigations during the flight of Spacelab 1 from 28 November - 8 December 1983.