Every day, your immune system performs a delicate balancing act, defending you from thousands of pathogens that cause disease while sparing your body's own healthy cells. This careful equilibrium is so seamless that most people don't think about it until something goes wrong.

Ross Colquhoun woke up his wife Mary E. Brunkow to tell her she won a Nobel Prize in medicine.

The Nobel winners unraveled an additional way the body keeps the system in check.