"Hearst Magazines and Yahoo may earn commission or revenue on some items through these links." The human immune system is a remarkable evolutionary tool that is often taken for granted—until, that is, ...

Food allergies are serious and, for some, potentially deadly. And yet, despite decades of research into allergies and what causes them, very little is known about why the vast majority of people are ...

Our immune system has a dark side: It’s supposed to fight off invaders to keep us healthy. But sometimes it turns traitor and attacks our own cells and tissues. What are called autoimmune diseases can ...