PLASMA DERIVED MEDIATORS

• Plasma derived mediators derived from interactions of 4 interlinked system-

1. Kinin system
2. Clotting system
3. Fibrinolytic system
4. Complement system

1. Complement system-

1. Classic pathway- activated by both IgM & IgG
2. Alternate pathway- activated by antibody

• Complement system functions-

1. C3a, C5a, C4a (anaphylatoxins) activates mast cells & basophils which releases histamine. (inflammation)

• Action- increase vascular permeability, phagocytosis.

1. C3b is an opsonin (opsonisation)
2. C5a is chemotactic for leukocytes.
3. Membrane attack complex (MAC) (C5b- C9) is a lipid dissolving agent (cell lysis) 

2. Kinin system-

• Activated by factor XIIa generate bradykinin (Hageman factor)
• Bradykinin effects includes-

1. Vasodilation
2. Increased vascular permeability
3. Pain

3. Clotting system

• Factor XIIa initiates the cascade of clotting system resulting in fibrinogen formation.
• Clotting activates fibrinolytic system.

4. Fibrinolytic system-

• Activated by plasminogen activator.
• Lately fibrinopeptides or fibrin is formed.