 This week on the International Space Station, astronaut Samantha Christopher Reddy conducted the triple-lux B experiment to monitor the function of immune cells in space. This is your space pod for April 8, 2015. The triple-lux B experiment uses immune cells from the blue muscle mytilus edulis to look at how well cells can perform phagocytosis in space. This is the process by which one cell engulfs or eats another cell or solid particle. In the case of immune cells, phagocytosis is used to attack foreign material, such as bacteria. Once the immune cell eats the bacteria, it destroys it by attacking it with toxic compounds known as free radicals, which, as you may remember from my video last week, can be pretty damaging to DNA. Specifically, these immune cells produce a group of free radicals known as reactive oxygen species. So how do we know if these toxic compounds are being produced by the immune cells? We use a compound called luminol. Luminol produces light in the presence of reactive oxygen species, and this light can be easily detected using a camera. We know how much reactive oxygen species are being produced by the amount of light that is detected by the camera. This experiment was conducted in the Columbus laboratory using the European Space Agency's Biolab Facility, which contains cameras, centrifuges, temperature-controlled cabinets, and other equipment needed for this study. This week, astronauts Samantha Christopher Reddy defrosted the cell culture from the onboard minus-80 degrees Celsius freezer and added it to a nutrient-rich broth. She then added a man-made compound called Zymosan, which is meant to simulate bacteria. I guess you could call it fake bacteria. Anyway, the cells were left to grow and ingest the compound, and the amount of light produced was measured. The video footage was sent to Earth for analysis. We don't have the results of the study just yet, but previous work on parabolic flights and centrifuge-simulated microgravity have shown that there is a decrease in reactive oxygen species formation. This could indicate that our cells are less capable of ingesting and destroying foreign material while in space. We already know that astronauts undergo many physical changes while in space, including muscle wastage, fluid shifts, and weakening bones. This has allowed us to enact countermeasures to these effects, such as on-orbit exercise programs. Understanding immune system responses in space means better healthcare for our astronauts. This is really important when we consider long-duration missions to the moon, Mars, and beyond. There is a risk of infection from opportunistic pathogens, where the normal bacteria that live on our skin and in our gut and normally cause us no problems can take advantage of our weakened immune systems. This is especially relevant when we consider that E. coli and Salmonella have been shown to become more lethal in microgravity. There is also a risk that human space travelers could transport microgravity-enhanced bacteria back down to Earth. The recently-launched one-year mission to the International Space Station will be monitoring astronaut gut-bacteria populations as part of the Twin Astronauts study. Finally, any advances in the knowledge of how our immune systems work in space will help people with weakened immune systems down here on Earth. There are so many experiments running aboard the International Space Station that it's hard to pick just one to explain in detail. Do you have a favorite experiment? If so, let me know in the comments below or via social media, and perhaps I'll talk about it in a future space pod. For more information about the triple-lux B experiment, check out the references in the description below. I'd like to thank everybody for watching, and I'd like to thank the patrons of tomorrow for helping contribute to making this video possible. If you love space pods and would like more information about how you can help crowd-fund this show, head over to patreon.com slash space pod. My name is Lisa Stodzianowski, I hope you enjoyed this video, and I'll see you next week.