Medicine & USMLE

Mast Cells

  1. Innate Immunity
  2. Adaptive Immunity
  3. Macrophages
  4. Neutrophils
  5. Dendritic Cells
  6. Mast Cells
  7. Eosinophils
  8. Basophils
  9. Natural Killer Cells
  10. Antigens
  11. MHC I and II
  12. Antibodies
  13. B Lymphocytes Overview
  14. B Cell Stages
  15. B-Cell Activation
  16. Plasma B-Cells
  17. Memory B-Cells
  18. T-Lymphocytes Overview
  19. T-Cell Stages
  20. Types of Activated T-Cells


Mast cells are a type of white blood cell found in the innate immune system. They function mainly as granulocytes, which means that they contain many little packets of chemicals called granules inside the cell. These granules importantly contain histamine, which is released in large amounts in the setting of an infection. While histamine release from granules is generally good for fighting infections, mast cells can mess up and sometimes recognize harmless things like pollen as foreign pathogens. When this happens, the release of histamine from mast cells is responsible for causing the symptoms of allergies.

Key Points

  • Mast Cells
    • Innate immune cell
    • Granulocyte
      • Mast cells can release the contents of their granules, which contain inflammatory chemicals like histamine
        • Histamine from mast cells plays a role in causing allergic reactions
    • Phagocyte
      • Mast cells are able to engulf foreign pathogens, especially parasites. Mast cells can also present antigens to T-cells. However, these are less common functions of mast cells.