Evolutionary Aspects of the Complement System

Abstract

The Complement System seems to have been specific to vertebrates. Studies carried out on the structure of entire genomes in some species, show that the Complement System genes of mammals have paralog counterparts in the protocordado amphioxus genomic models that would correspond to the genetic common origin of tetrapods. In agnathans,and lampreys, primitive functions survive: genes and proteins of this system. It is important the finding of other systems functionally analogous to those of the Complement in different species. The Complement is closely asso- ciated to the immune function response, to inflammatory phenomena and to coagulation. The main antimicrobial mechanism is the lysis of foreign cells through a cascade of factors. From an evolutionary point of view, the Complement changed from being an independent effector mechanism at the origin of vertebrates, to being associated with lytic and antiinflammatory immune responses. The observations and study of these effector mechanisms of anamniote vertebrates offers a view into the evolutionary past.