the binding of *complement to the complex that is formed when an antibody reacts with a specific antigen. Because complement is taken up from the serum only when such a reaction has occurred, testing for the presence of complement after mixing a suspension of a known organism with a patient’s serum can give confirmation of infection with a suspected organism. The *Wassermann reaction for diagnosing syphilis is a complement-fixation test.
A large body of blood proteins (over 20), initiated in the liver, and intimately involved in nearly all aspects of immunity and nonspecific resistance. They form two types of self-mediated cascade reactions to antigens, antibody-antigen complexes, dead tissue and the like, and are almost solely able to initiate the rupture and killing of bacteria. The protein strings they form around foreign substances are the main “hooks” used for absorption by macrophages as they digest and clean up.... complement
This is part of the body’s defence mechanism that comprises a series of 20 serum peptides (see PEPTIDE). These are sequentially activated to produce three signi?cant effects: ?rstly, the release of small peptides which provoke in?ammation and attract phagocytes (see PHAGOCYTE); secondly, the deposition of a substance (component C3b) on the membranes of invading bacteria or viruses, attracting phagocytes to destroy the microbes; thirdly, the activation of substances that damage cell membranes – called lytic components – which hasten the destruction of ‘foreign’ cells. (See IMMUNOLOGY.)... complement system
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