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