Complement System
The complement system plays an important role in host defense against infectious agents, as well as, in the infla-mmation process. This system is comprised of numerous plasma proteins that act as an enzyme or binding protein. The complement system includes distinct cell-surface receptors that are specific for physiological fragments of complement proteins. The classical pathway is the major effector of antibody action. The activation of this pathway promotes opsonophagocytic killing, serum bactericidal activity, and removal of immune complexes.
Pathway400-901-9800
www.bioss.com.cn
Kinase Phosphatase Ligand Transcription FactorOther Receptor Phospho Activation
Membrane Cell Function Binding/Association
Activation Inhibition Indirect Effect Dissociation
P
C4BP, CD46, FactorI
C3b
C4b
C2b
C4b
C2a
C2bC3b
C4a
CR1, CR2, MCP, CD46, FactorI C5
C5b
C5a
C5b
C7C6
C6
C7
C8
C9
C3
C3a
C3b
C3b
C3b
FactorD
FactorBBb
Ba FactorH
Bb
DAFBb
C3a C3a
C3
C4
C2
C5 convertase
C5 convertase
C3 convertase
Plasma membrane
Membrane Attack Complex (MAC)
CD59
C9C9 C9C9C8
ALTERNATIVE PATHWAYCLASSICAL PATHWAYC1 Complex
IgGIgG
Microbe surface
C5b
C6C7C8 C9 C9 C9 C9
C9
Microbe