New research suggests that space travel can weaken the immune system by altering the expression of genes related to immune functions. A study by the University of Ottawa found that the expression of many genes related to immune functions rapidly decreases when astronauts reach space, while the opposite happens when they return to Earth after six months aboard the International Space Station (ISS). The researchers studied gene expression in leukocytes (white blood cells) in a cohort of 14 astronauts, including three women and 11 men, who resided on board the ISS for between 4.5 and 6.5 months between 2015 and 2019. Leukocytes were isolated from 4 milliliters blood drawn from each astronaut at 10 time points: once pre-flight, four times in flight, and five times back on Earth. The research was funded by the Canadian Space Agency.
