Space flights might risk astronauts\' immune systems

Humans might consider venturing into space to be a bold adventure but it may not be good for our immune systems, researchers in California say. A study by researchers at the University of California, Davis, shows how growing up on a space shuttle weakened a key arm of the immune system in Drosophila flies, which share many fundamentals of that system with mammals such as mice and humans. The flies were sent into space as eggs on a 12-day mission aboard the Space Shuttle Discovery, where they hatched and grew into adults in about 10 days. After they returned to Earth, UC Davis biologist Debora Kimbrell and colleagues tested their responses to two different infections, a fungus and a bacterial infection. Any immune resistance to the fungus was "non-functional" in the space-raised flies, they found. It's well established spaceflight and zero gravity affect immune responses, Kimbrell said, suggesting future spacecraft designed for long missions should include centrifuges a crew could use to not only keep up bone and muscle mass but keep their immune systems operating normally.