Inflammation : Chemical mediators

Chemical mediators

Histamine
- Stored in granules of basophils, mast cells, platelets
  - Causes vasodilation and increased capillary permeability
Serotonin
- Stored in platelets, mast cells, enterochromaffin cells of GI tract
  - Causes vasodilation and increased capillary permeability like histamine.
  - Stimulates smooth muscle contraction
Kinins (e.g., bradykinin)
- Produced from precursor factor kininogen as a result of activation of Hageman factor (XII) of clotting system
  - Cause contraction of smooth muscle and vasodilation.
  - Result in stimulation of pain
Complement system (C3a, C4a, C5a)
- Anaphylatoxic agents generated from complement pathway activation
  - Stimulate histamine release and chemotaxis
  - Final components of complement system create holes in cell membrane, causing targeted cell death by membrane rupture
Prostaglandins and leukotrienes
- Produced from arachidonic acid
  - PGs cause vasodilation. LTs stimulate chemotaxis
Cytokines

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