immune disorders
Innate Immunity
Complement System
The complement system consists of more than 30 proteins that act in a sequence: One protein activates another, which activates another, and so on to defend against infection. This sequence is called the complement cascade. Complement proteins have many functions in acquired immunity as well as innate: Killing bacteria directly Helping destroy bacteria by attaching to them and thus making the bacteria easier for neutrophils and macrophages to identify and ingest Attracting macrophages and neutrophils to a trouble spot Neutralizing viruses Helping immune cells remember specific invaders Promoting antibody formation Enhancing the effectiveness of antibodies Helping the body eliminate dead cells and immune complexes (which consist of an antibody attached to an antigen) 