the complement Flashcards
(7 cards)
1
Q
what is the complement
A
the humoral part of the innate immune system
2
Q
what does the complement do
A
it stimulates inflammation, it destroys cells and is part of opsonisation
3
Q
what can the complement be activated by
A
the classical and alternative pathway
4
Q
what components are part of the complement
A
many foreign, soluble, serum proteins C1-C9
5
Q
what are the three pathways
A
classical, alternative and lectin pathways
6
Q
describe the classical pathway
A
- C1 becomes activated when binds to a antigen-antibody complex
- C1 then cleaves C2 into C2a and b and cleaves C4 into C4a and b
- C2b and C4b react to form C3 convertase
- C3 convertase then cleaves C3 to form C3a and b
-c3b attaches to c3 convertase to form c5 convertase
-c5 convertase hydrolyses c5 to c5a and c5b
-c5b attaches to c6 and membrane attack complex is formed
7
Q
describe the alternative pathway
A
- endotoxin polysaccharides or cell wall components bind to C3b
- C3a and b are always being made from C3 but if no activation occurs then they will be destroyed
- when C3b binds to endotoxin polysaccharides they
Lecture way - spontaneous hydrolysis of c3 into c3 a and c3b
-c3 convertase is made by factor b + c3b + mg then cleavage = c3 convertase
-c3 is stabilised by binding to properdin - c5b forms membrane attack complex by further binding to complement components (until c9)
