HUMAN CELLULAR IMMUNE RESPONSIVENESS FOLLOWING SPACE-FLIGHT

Abstract

Peripheral circulating lymphocytes were separated from astronaut blood samples 3 times before and 2 times after the first 4 USA Space Shuttle flights. The ability of the in vitro T lymphocytes to respond to phytohemagglutinin by blastogenesis was reduced for each crewmember following spaceflight. The astronauts experienced a postflight increase in neutrophils and a decrease in eosinophils. These postflight changes in leukocytes increased with subjectively-evaluated increases in the incidence of inflight stress, indicating that stress, and not hypogravity, is likely to be the major effector of these changes.