Complement System

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Complement System
2013-11-17 11:24:44
Complement System

Complement System
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  1. What is the complement system?
    Major pathway acting to protect against infection and inflammation
  2. What triggers a cascade?
    Interaction with complement components with each other in an enzyme
  3. What are zymogens?
    • Protease (complement component)
    • require activation by enzyme cleavage
  4. Function of the complement system?
    • Production of opsinin
    • Production of anaphylatoxins
    • Direct Killing of pathogens
    • Others: Maintenance to homeostasis, enhancing Ag-specific immune response
  5. Function of opsinin?
    enhance phagocytosis of particles by macrophage and neutrophils
  6. How do opsinin work?
    • Coat bacteria which are then recognised by specific receptors on phagocytes (macrophages, neutrophils)
    • Trigger phagocytosis of bacteria
  7. Products of the complement cascade?
  8. What do opsinin stimulate?
    phagocytosis of bacteria (MOST IMPORTANT COMPLEMENT FUNCTION)
  9. What are anaphylatoxins?
    Peptide/fragments from cleavage of complement protein
  10. What do anaphlatoxins do?
    Induce local and systemic inflammatory response
  11. Anaphylatoxins bind to many cell types. Give an example and what occurs?
    • Bind to neurophils
    • Stimulate directional migration
    • migrate from area of lesser conc to area of higher conc
    • chemotatic for neutrophils --> more phagocytes recruited to site of complement activation
  12. What are the 3 pathways of active complement?
    • Classical pathway
    • Mannose-binding Lectin (MB-Lectin) pathway
    • Alternative pathway
  13. How is the classical pathway initiated?
    binding of C1q to pathogen surface
  14. How is mannose-binding lectin pathway initiated?
    binding of mannose-binding lectin to carbohydrates on bacteria/virues
  15. How is the alternative pathway initiated?
    Binding of spontaneously active C3 in plasma to pathogen surface