T-cells
In honor of the great Scienceblogs migration, and inspired by Ethan's wonderful post about the migration of the universe, I thought I would talk about something on a smaller scale: cell migration.
The scale is small, but the problem is huge. Most of your organs are locked in place - your heart never needs to be in your thigh - but the immune system has to be everywhere. When you cut your toe, breathe a virus into your lungs or eat a piece of contaminated spinach, the immune system needs to be johnny-on-the-spot with the inflammatory response.
Thankfully, there's already an organ system that…