Immune system becomes 'confused' during spaceflight

A new study has revealed that spaceflight may temporarily alter the immune system of crew members flying long duration missions aboard the International Space Station, leaving it "confused".

According to the findings of two NASA collaborative investigations, the distribution of immune cells in the blood of crew members aboard the space station is relatively unchanged during flight, however, some cell function is significantly lower than normal, or depressed, and some cell activity is heightened.

When cell activity is depressed, the immune system is not generating appropriate responses to threats. This may also lead to the asymptomatic viral shedding observed in some crew members, which means latent, or dormant, viruses in the body reawaken, but without symptoms of illness. When activity heightens, the immune system reacts excessively, resulting in things like increased allergy symptoms and persistent rashes, which have been reported by some crew members.

Researcher Brian Crucian said that prior to the Integrated Immune study, little immune system in-flight data had been collected and 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.

According to Crucian, the immune system is likely being altered by many factors associated with the overall spaceflight environment. Things like radiation, microbes, stress, microgravity, altered sleep cycles and isolation could all have an effect on crew member immune systems and if this situation persisted for longer deep space missions, it could possibly increase risk of infection, hypersensitivity, or autoimmune issues for exploration astronauts.

The findings were published in the Journal of Interferon and Cytokine Research.