Complement-L7 Flashcards
End result of complement pathways
Cleavage of C3 eventually leading to cell lysis.
Complement
Term for a complex system of sequentially interacting serum proteins. Activation of the complement cascade results in cell lysis, increased phagocytosis, increased vascular permeability, enhanced leukocyte chemotaxis and functional stimulation of macrophages.
Membrane attack complex
Components C5-C9, lyses the target cell
C3a
Recruits phagocyte
C3b
Tags bacterium for destruction
Alternative pathway
- Pathogen surface creates local environment conducive to complement activation
- First to act
Classical pathway
- C reactive protein or antibody binds to specific antigen on pathogen surface
- IgM binds antigen on a pathogen surface
- Third to act
Consequences of C3 being cleaved to C3a and C3b
- Recruitment of inflammatory cells
- Opsonization of pathogens, facilitating uptake and killing by phagocytes
- Perforation of pathogen cell membranes
- Death of pathogen
CR1
- Ligand:C3b, C4b
- Stimulates phagocytosis and erythrocyte transport of immune complexes
CR2
-Part of B cell co-receptor
CR3
-Stimulates phagocytosis
CR4
-Stimulates phagocytosis
Anaphylatoxin
- C3a, C5a
- Histamine release for mast cells
- Increase vascular permeability
Chemotaxis
- C5a
- Attract polymophonuclear leukocytes and macrophages
Opsonization
- C3b
- Increased phagocytosis of particles by granulocytes and macrophages
