Emergent Behaviour in T Cell Immune Response

Abstract

The ability of our immune system to fight off challenges posed by pathogenic agents (external or internal) is amazing. Indeed, many times during a normal lifespan immune cells have to identify and destroy incoming threats while leaving harmless cell trafficking undisturbed. Most remarkably, this careful regulation of body function is achieved in the absence of any organ in charge of controlling immune response. The latter is just an emergent property resulting from a very limited number of individual actions taken by immune cells, using only local information from their immediate neighbourhood. We shortly review here some striking aspects of this emergent behaviour. In particular, we will focus our attention on two issues, namely the way immune system regulates the number of effector T cells required to wipe out an acute infection and the mechanisms to distinguish friends from foes upon inspection of circulating antigens.