1. A very complex system of about 50 different proteins found either in serum or as receptors on white cells
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2. What is the complement system equation?
2. C3=C3b+C3a
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3. What does deficiency in C3 cause?
3. Recurrent bacterial infections
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4. What happens to C3b?
4. Gets deposited on surface of micro organisms and marks it out for destruction
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5. What is the first component of the classical pathway?
5. C1q, hexavalent, arrangement of 18 polypeptides 6 collagenous base and arm regions connected to 6 globular heads
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6. What is the first component of the classical pathway activated by?
6. Activated by IgG and IgM
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7. What is the sequence of events in the classical pathway?
7. C1r and C1s then bind C1q. C1r and C1s become proteolytic enzymes. C4 and C2 cleaved. C3 convertase formed
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8. What is C3 convertase full name?
8. C4b2a
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9. What is mbl, what does it do?
9. Mannose binding lectin. Binds sugars. Molecules. Found in repeating arrays on microbial surfaces
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10. What is the lectin pathway activation?
10. A C3 convertase is formed (C4b2a). C3 is cleaved. C3b fragments bind to surface
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11. What happens in Lysis?
11. C3b leaves C5 to C5b and C5a. C5b binds to surface of micro organism, 4 other proteins (C6, C7,C8,C9) bind. Membrane attack complex (MAC) formed. Forms funnel shaped hole in cell membrane
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12. How does alternative pathway work ?
12. C3 spontaneously splits into C3a and C3b. c3b joins with protein B to make C3bBb (in the precence of factor D) which is C3 convertase and can catalyse c3-c3a+c3b reaction OR. Bind with C3b to make C3bBb3b which is C5 convertase
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13. What are C3a and C5a?
13. anaphylatoxions
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14. What is the sequence for anaphylaxis?
14. C3a binds to receptors on mast cells- histamine release, vascular permeability increases- recruitment of other components of inflammatory response to infection site
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15. What triggers chemotaxis?
15. C5a binds to C5a receptors on phagocytes. Phagocyte migrates up concentration gradient of C5a to infection site. Phagocyte becomes stickier. Phagocytes stop moving and move through endothekium towards infection in underlying tissues
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16. What is the neutrophil transmigration to site of infection in tissues
16. Rolling and tethering, adherence, rolling arrest, transmigration and migration into underlying tissues moving towards higher concetrations of C5a
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