What role do the appendix and tonsils play?

We put this to Professor Adrian Newland:

Adrian - The gut has lots of areas of immune system throughout it to try and deal with any infections that come in through the mouth and go down into the gut. The tonsils themselves are particularly important early on in life. That is one of the reason kids and teenagers have such problems with their tonsils. They get exposed to airborne bugs. They stimulate the tonsils to develop immunities to those bugs and the tonsils get bigger and cause bouts of tonsillitis. Helen - I had my tonsils out when I was little and it wasn't very nice at all. Since then I've been absolutely fine.