SKI immunologist Gretchen Diehl
The immune system’s main job is identifying things that can make us sick. In the language of immunology, this means distinguishing “self” from “non-self”: The cells of our organs are self, while disease-causing bacteria and viruses are non-self.
But what about the billions of bacteria that live in our guts and provide us with benefits like digesting food and making vitamins? Are they friend or foe?
This isn’t only a philosophical question. An immune system that mistakes our good gut bacteria for an enemy can cause a dangerous type of inflammation in the intestines called colitis. An immune system that looks the other way while gut microbes spill past their assigned borders is equally dangerous. Understanding how the immune system learns to make a brokered peace with its microbial residents, called the microbiota, is therefore an important area of research.