NASA Finds Long-Term Spaceflight Confuses the Immune System
In order to measure immune activity in astronauts, the researchers studied their blood plasma before, during, and after space missions. "Prior to the Integrated Immune study, little immune system in-flight data had been collected," said Brian Crucian, NASA biological studies and immunology expert. "Previous post-flight studies were not enough to make any determination about spaceflight's effect on the immune system. This in-flight data provided the information we needed to determine that immune dysregulation does occur and actually persists during long-duration spaceflight."
Their data showed that while the distribution of immune cells remained the same, the activity of those cells went haywire in space. Some cells' activity would be depressed, while others' activity would be exacerbated. Both of these instances of dysregulation pose problems for the astronauts, as depressed immune cells will not respond appropriately to contaminants while cells with heightened activity may cause disproportionate immune reactions, like allergy symptoms and chronic rashes. Both of these immune overreactions could be found in the anecdotal accounts of the astronauts' health. Their study also found that the concentration of cytokines, immune cells that initiate the process of inflammation, varied significantly during spaceflight, which seemed to confirm the results.
According to Crucian, there are many factors inherent to spaceflight that can cause these irregularities: "Things like radiation, microbes, stress, microgravity, altered sleep cycles and isolation could all have an effect on crew member immune systems. If this situation persisted for longer deep space missions, it could possibly increase risk of infection, hypersensitivity, or autoimmune issues for exploration astronauts."
Although Crucian speculates that there is an increased risk of health problems, this study does not confirm that notion by itself. NASA Human Research Program Chief Scientist Mark Shelhamer emphasizes that more work needs to be done in order to gauge the ramifications of these immune differences during spaceflight. "These studies tell us that this is an important issue and that we are measuring the right things," said Shelhamer. "They also tell us there is no place during spaceflight where we see stabilization of the immune system. This is critical as we pursue longer duration missions and why we are studying this further during the upcoming one-year mission."