How T Cells Find Their Way Around

Among diverse cellular systems of the body, the immune system is unique in representing a network of interacting cells of enormous complexity yet based on single cells travelling around. Only the advanced visualization technologies of the recent years have brought to everybody’s attention the fact that what we see is usually a snapshot of a dynamic system, where the majority of players are highly motile and become coordinated by diverse signals provided by their environment. This introductory chapter touches a selection of aspects that address predominantly the functioning of the system as such. It attempts to provide a framework of how migratory mechanisms are regulated to ensure that various cell populations reach their destination and that the appropriate interaction partners find each other.