Learning Center Articles

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