INFLAMMATION
PLASMA PROTEIN–DERIVED MEDIATORS Of Inflammation
PLASMA PROTEIN–DERIVED MEDIATORSOF INFLAMMATION
4 types
Complement Kinin Fibrinolyt
icCoagulati
on
DEFINITION
Any messenger that acts on blood
vessels, inflammatory cells or other
cells to contribute to an
inflammatory response.
PLASMA-DERIVED MEDIATORS( PLASMA PROTEASES )
4 INTERRELATED SYSTEMS ARE ACTIVE WITHIN THIS CATEGORY :
* COMPLEMENT SYSTEM.* K ININ SYSTEM.* CLOT TING SYSTEM.* F IBRINOLYTIC SYSTEM.
All of these systems are produce by the host
( Endogenous )
1) THE COMPLEMENT SYSTEM
The complement system is a cascade
system of enzymatic proteins
Q: What does complement
do?
The most important function of complement is the elimination of pathogens and harmful antigens.
A C T I VAT I O N T H E C O M P L E M E N T S Y S T E M .I T C A N B E A C T I VAT E D D U R I N G T H E A C U T E
I N F L A M M AT O RY R E A C T I O N I N S E V E R A L WAY S :
• In tissue injury, enzymes capable of activating complement are released from injured cells.
• During infection, the formation of antigen-antibody complexes can activate complement via the classical pathway.
• The endotoxins of Gram-negative bacteria activate complement via the alternative pathway.
• Carbohydrate molecules on the surface of infectious agents activate complement by the "Lectin Pathway".
• Products of the kinin, coagulation and fibrinolytic systems can activate complement.
T H E P R O D U C T S O F C O M P L E M E N T A C T I VAT I O N M O S T I M P O RTA N T I N A C U T E
I N F L A M M AT I O N I N C LU D E:
• C5a: chemotactic for neutrophils; increases vascular
permeability; releases histamine from mast cells
• C3a: similar properties to those of C5a, but less active
• C56789: cytolytic activity (membrane attack complex)
• C3b: opsonization of bacteria (facilitates phagocytosis
by macrophages).
2 ) THE KININ SYSTEM
The kinins are peptides of 9-11 amino acids
Bradykinin is also a chemical
mediator of pain, a cardinal feature of
acute inflammation.
the most important vascular permeability factor is bradykinin.
The kinin system is activated by coagulation factor XII (Hageman factor) .
3) COAGULATION SYSTEM
The coagulation system is responsible
for the conversion of soluble
fibrinogen into fibrin, a major
component of the acute inflammatory
exudate.
Coagulation factor XII (Hageman factor), once activated
by contact with extracellular materials such as basal lamina,
and various proteolytic enzymes of bacterial origin, can
activate the coagulation, kinin and fibrinolytic systems.
4 ) FIBRINOLYTIC SYSTEM
Plasmin is responsible for the Iysis of
fibrin into fibrin degradation products,
which may have local effects on vascular
permeability (increases vascular
permeability) .
KHALID IBRAHIM BAHNI AL-SHIKHY
I.D No. : 431801993