Which cell type contains granules rich in histamine and heparin?

Which cell type contains granules rich in histamine and heparin?

• A. Macrophages
• B. Fibrocytes
• C. Chondrocytes
• D. Mast cells

Answer: (D)

Granules rich in histamine and heparin identify a specific tissue-resident immune cell that mediates immediate allergic and inflammatory responses. Mast cells sit in connective tissue near blood vessels and mucosal surfaces, ready to release their granule contents when activated by allergens or IgE cross-linking. Histamine in these granules causes rapid effects like vasodilation and increased vascular permeability, contributing to redness, swelling, and itching. Heparin helps prevent local clotting, aiding the movement of other immune cells to the site of inflammation. Macrophages, fibrocytes, and chondrocytes have very different roles and do not store histamine and heparin in conspicuous granules. Macrophages are phagocytes that engulf pathogens and modulate inflammation, fibrocytes maintain and remodel connective tissue, and chondrocytes produce cartilage matrix. The presence of these granules is a hallmark feature of mast cells, making them the correct choice.

Granules rich in histamine and heparin identify a specific tissue-resident immune cell that mediates immediate allergic and inflammatory responses. Mast cells sit in connective tissue near blood vessels and mucosal surfaces, ready to release their granule contents when activated by allergens or IgE cross-linking. Histamine in these granules causes rapid effects like vasodilation and increased vascular permeability, contributing to redness, swelling, and itching. Heparin helps prevent local clotting, aiding the movement of other immune cells to the site of inflammation.

Macrophages, fibrocytes, and chondrocytes have very different roles and do not store histamine and heparin in conspicuous granules. Macrophages are phagocytes that engulf pathogens and modulate inflammation, fibrocytes maintain and remodel connective tissue, and chondrocytes produce cartilage matrix. The presence of these granules is a hallmark feature of mast cells, making them the correct choice.