9 Comp Sys

Question 1

Three pathways of the complement system

Answer 1

1. Classical
   - Initiated by Ag-Ab complex
2. Alternative
   - Initiated by polysaccharides of invading microorganisms in the absence of Ab or aggregates of IgA
3. Lectin
   - Initiated by pathogen associated carbohydrate structures: Mannose binding lectin (MBL)

Question 2

C1 components

Answer 2

C1q,r,s
C1s+C1r = 8 shape which fits over knobs of C1q

In the presence of Ca2+, C1 binds to Ab-Ag complex on microbial membrane = activated

Question 3

Part of complement system that is anaphylatoxin

Answer 3

C3a = binds to mast cells causing the release of histamine; (C4a and C5a also potent anaphylatoxin)

Question 4

Mechanisms

Answer 4

-

Question 5

Inhibitors

Factor I

Factor H

C1-INH

DAF or CRI

Factor S

Answer 5

-