complement
A heat-labile system of enzymes in plasma associated with response to injury. Activation of the complement cascade occurs through two convergent pathways. In the classical pathway the formation of antibody/antigen complexes leads to binding of C1, the release of active esterase that activates C4 and C2 that in turn bind to the surface. The C42 complex splits C3 to produce C3b, an opsonin, and C3a (anaphylatoxin). C423b acts on C5 to release C5a (anaphylatoxin and chemotactic factor) leaving C5b that combines with C6789 to form a cytolytic membrane attack complex. In the alternate pathway C3 cleavage occurs without the involvement of C142, and can be activated by IgA, endotoxin, or polysaccharide-rich surfaces (eg. yeast cell wall, zymosan). Factor B combines with C3b to form a C3 convertase that is stabilized by Factor P, generating a positive feedback loop. The alternate pathway is presumably the ancestral one upon which the sophistication of antibody recognition has been superimposed in the classical pathway. The enzymatic cascade amplifies the response, leads to the activation and recruitment of leucocytes, increases phagocytosis and induces killing directly. It is subject to various complex feedback controls that terminate the response.

Dictionary of molecular biology. 2004.

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  • complément — [ kɔ̃plemɑ̃ ] n. m. • 1308; de l a. fr. complir « remplir »; repris 1690; lat. complementum, de complere « remplir » 1 ♦ Ce qui s ajoute ou doit s ajouter à une chose pour qu elle soit complète. ⇒ achèvement, couronnement. Le complément est… …   Encyclopédie Universelle

  • complement — COMPLEMÉNT, complemente, s.n. 1. Ceea ce se adaugă la ceva spre a l întregi; complinire. 2. Parte secundară a propoziţiei care determină un verb, un adjectiv sau un adverb. 3. Substanţă de natură proteică prezentă în serul normal şi care… …   Dicționar Român

  • Complement — Complément Cette page d’homonymie répertorie les différents sujets et articles partageant un même nom …   Wikipédia en Français

  • complement — COMPLEMENT. s. m. Ce qui s ajoute à une chose pour lui donner sa perfection. On dit en Théologie, Complément de béatitude, pour exprimer Le comble de la beatitude. La résurrection des corps sera le complément de la béatitude des Saints.Complément …   Dictionnaire de l'Académie Française 1798

  • complement — n Complement, supplement are comparable both as nouns meaning one thing that makes up for a want or deficiency in another thing and as verbs meaning to supply what is needed to make up for such a want or deficiency. Complement implies a… …   New Dictionary of Synonyms

  • Complement — Com ple*ment, n. [L. complementun: cf. F. compl[ e]ment. See {Complete}, v. t., and cf. {Compliment}.] 1. That which fills up or completes; the quantity or number required to fill a thing or make it complete. [1913 Webster] 2. That which is… …   The Collaborative International Dictionary of English

  • complement — complement, compliment, complementary, complimentary 1. Complement and compliment each function as noun and verb; in pronunciation they are largely indistinguishable except that in the verbal function compliment has a fuller i sound in its second …   Modern English usage

  • Complement — (v. lat. Complementum), 1) Ergänzung; 2) (Math.), C. einer Größe ist im Allgemeinen das, was zu dieser addirt werden muß, um ein gewisses Ganze zu erhalten. Complement eines Winkels od. Kreisbogens ist beziehungsweise derjenige Winkel od. Bogen,… …   Pierer's Universal-Lexikon

  • complement — ► NOUN 1) a thing that contributes extra features to something else so as to enhance or improve it. 2) the number or quantity that makes something complete. 3) a word or words used with a verb to complete the meaning of the predicate (e.g. happy… …   English terms dictionary

  • complement — (n.) late 14c., that which completes, from O.Fr. compliement accomplishment, fulfillment (14c., Mod.Fr. complément), from L. complementum that which fills up or completes, from complere fill up (see COMPLETE (Cf. complete)). Originally also… …   Etymology dictionary

  • complement — [n] companion, counterpart accompaniment, addition, aggregate, augmentation, balance, capacity, completion, consummation, correlate, correlative, counterpart, enhancement, enrichment, entirety, filler, finishing touch, makeweight, pendant, quota …   New thesaurus

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