Long Spaceflights Affect the Immune System

Scientists have studied the effects of staying in outer space for prolonged periods of time, and thus far they managed to derive some pretty worrying conclusions. A new research adds to the growing body of evidence indicating the spending a lot of time in microgravity can harm the human immune system.

These connections hold true even if astronauts take special measures to ensure that they do not fall ill while on a shuttle, or the International Space Station (ISS). Even with these preparations, their immune systems still fall victim to the unfamiliar circumstances of outer space.

The recent investigation was carried out on astronauts who had returned to Earth from long-term stays on the ISS, as part of 6-month-long expeditions. All of them were found to be more susceptible to developing diseases once they returned home.

One of the most interesting effects was that a reduction of the number of antibodies these astronauts had in their blood streams. These molecules are the primary line of defense the human body has against attack from foreign contaminants, such as bacteria and microbes.

This weakening of the immune system, the researchers say, needs to be addressed by space agencies around the world as soon as possible. This van be done either through drugs, or by adopting nutritional measures that are more in tune with the new demands and environment.

The research was conducted by French experts with the Université Henri Poincaré-Nancy. The efforts were coordinated by research scientist Jean-Pol Frippiat, Space reports. The expert says that a process called somatic hypermutation was the most severely affected.

This process refers to how fast antibodies can mutate their genes so that they can become able to bind to invading microorganisms. In order to study this aspect, the team sent a group of salamanders to space, and kept another one for comparison on Earth.

Both groups were then injected with a protein extracted from cows. In the salamanders that were kept in space, the rate of somatic hypermutation was significantly lower than in their counterparts in France.

Analysts agree that this investigation “brings together yet more evidence that the immune system is dependent on gravity,” says.expert Millie Hughes-Fulford, who is a NASA science astronaut and molecular biologist.

“Dependence on gravity should be no surprise since all of Earth's jawed vertebrates developed in Earth's gravity, and it would be logical to expect that some systems would require gravity for normal function,” the expert adds.

Details of the work appear in the latest online issue of the FASEB Journal.