Enzymatic activity
C1r C1s C2a Bb D
Inflammatory activity
C4a
C3a
C5a
MAC
C5b C6 C7 C8 C9
Classic pathway
1 4 2 3 5-9 MAC
Lectin
4
2
3
Alternative
3 (spontaneous , slow, small amnts)
B
D
MAC formation
After C3 C4b2a Amplification C4b2a3b 5-9 MAC
Pathways converge at
C3
Activation of classic pathway
IgM ***
IgG1,3
Protein binding activity
C1q
C4b
C3b
Anaphylatoxins
C5a>C3a>C4a
Stimulate cellular de granulation
Chemo tactic for neutrophils
C1
Binds directly to pathogen or to Ab (indirect)
C3 convertase
CP
C4b2a
C5 convertase
CP
C4b2a3b
Endogenous complement inhibitors
DAF
MCP
C1 inhibitor