The complement system: Pathophysiology and clinical relevance

In the present article we review selected aspects of the complement system as a major determinant of innate immunity. Besides a detailed description o f the components of the complement system, its mode of action, cellular rec eptors and regulatory control mechanisms, we have focused on the role of th e complement system in mutual defence strategies of invading viral pathogen s and the host. Since a detrimental activation of the complement cascade is a critical element of several pathological conditions in diverse organs, w e summarise the role of a deteriorated complement system in dermatology, ne phrology, neurology and xenotransplantation.