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