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16 Cards in this Set

  • Front
  • Back
The name for complement was coined by who?
Paul Erlich
What are the functions of the complement cascade?
1. Lysis of cells, bacteria, viruses

2. Opsonization to promote phagocytosis of Ag

3. Activation of inflammatory response

4. Clearance of immune complexes
What are the 3 complement pathways?
1. Classical
2. Alternative
3. Lectin
What initiates the classical pathway?
Ag-Ab complexes or bacterial cell wall
Describe the classical pathway.
1. C1 cleaves C4 into C4a and C4b
2. C1 cleaves C2 into C2a and C2b
3. C4b binds to pathogen surface
4. C4b binds C2a
5. C4bC2a cleaves C3 into C3a and C3b
6. C3b binds to pathogen surface
7. C3b cleaves C5 into C5a and C5b
8. C5b activates and cleaves C6-C9
9. C9 forms the pore in a pathogen cell membrane (MAC)
Describe the alternative pathway.
1. C3b binds to bacterial cell
2. C3a promotes inflammation, C3b promotes opsonization
3. C5-C9 promotes cell lysis
The 3 complement pathways are components of what immune system?
classical - acquired

alternative - innate

lectin - innate
Which complement pathway(s) do not require Ab-Ag complexes?
alternative and lectin
Factor B, D and properdin are ONLY a part of which complement pathway?

properdin is important for stability of pathway
What activates the lectin pathway?
binding of mannose-binding lectin, an acute phase protein found on the surface of microorganisms
Describe the lectin pathway?
1. MBL cleaves C4 and C2
2. activates complement (C5-C9)
What can MAC lyse?
gram-negative bacteria and viruses

gram positive bacteria are generally resistant to MAC b/c they have thick peptidoglycan coats and MAC has trouble putting a hole in it
C3a and C5a are involved in what kind of response?
allergic responses

degranulation of eosinophils
People with C1 and C4 deficiencies tend to suffer from what?
rheumatologic and vascular-collagen diseases
People with C3 deficiencies are more susceptible to what?
bacterial infections
What is a C2 deficiency associated with?
chronic neutropenia