[The complement system and its biological activities].

The complement system is a non specific humoral defence mechanism which can be triggered by various effectors : immune-complexes, extrinsic proteases, bacterial cell-wall polysaccharides, viral membranes. Different peptides or multimolecular complexes are formed by a cascade of proteolytic cleavages; they take an active part in the inflammatory response and may contribute to different pathological manifestations.