The "contact system" in health and disease

In the last 10 years, our understanding of the contact system, particularly its biochemistry, has greatly increased. The components of this system and their interactions have been elucidated from in vitro experiments. Although the activation of the contact system have been implicated in various types of human disease, in only a few instances is its role clearly defined. The physiologic role of the contact system is totally unknown at present. Obviously, more studies are needed to bridge a big gap between in vitro observations and in vivo phenomena.