Question: What is the most intersting thing you have learned about the immune system?

Mark Travis answered on 13 Jun 2010:

Hello there,
The most interesting thing we have discovered about the immune system is a key role for a particular set of molecules in preventing inflammatory bowel disease.
Did you know we have around 100 trillion bacteria living in or intestine? These are very important in helping us keep heathy and digest food. But, the immune system is always poised to attack bacteria that enter the body that may cause us harm. So, how does the immune system know how to attack harmful bacteria that infect us, but ignore the ‘good’ bacteria that lives in the gut? When this regulation doesn’t work properly, the immune system attacks our own body, and causes inflammatory bowel disease. We have identified an important pathway that prevents this from happening.