How does stress make you sick?

The Holmes- Rahe Stress Inventory has been around for years. I remember it from one of my college psychology classes. The idea is that if you score over a certain level on this survey chances are you'll get sick in some way, pretty soon. Intuitively it makes sense and there are multiple lines of evidence, some strong and some not so strong, as to various mechanisms. One, according to a recent study, is telomere shortening.