mast cell granule

Definition

Target type: cellularcomponent

Coarse, bluish-black staining cytoplasmic granules, bounded by a plasma membrane and found in mast cells and basophils. Contents include histamine, heparin, chondroitin sulfates, chymase and tryptase. [GOC:jl, http://www.ijp-online.com/archives/1969/001/02/r0000-0000tc.htm, PMID:12360215]

Mast cell granules are membrane-bound organelles found in the cytoplasm of mast cells, specialized immune cells that play a critical role in allergic and inflammatory responses. They are characterized by their dense, electron-dense appearance under microscopy and contain a diverse array of preformed mediators that are released upon cell activation. The cellular component of mast cell granules can be broadly categorized into three main types:

1. **Histamine:** A potent vasoactive amine that causes vasodilation, increased vascular permeability, and smooth muscle contraction. It contributes to the characteristic symptoms of allergies, such as sneezing, itching, and runny nose.

2. **Proteases:** These enzymes, including tryptase, chymase, and carboxypeptidase, are stored in granules and released upon activation of the mast cell. They play a role in tissue remodeling, inflammation, and the degradation of extracellular matrix proteins.

3. **Other mediators:** In addition to histamine and proteases, mast cell granules contain a variety of other mediators, including:

* **Heparin:** A glycosaminoglycan that acts as an anticoagulant and also plays a role in regulating inflammation.

* **Cytokines:** These signaling molecules, such as TNF-α and IL-4, are involved in the recruitment and activation of other immune cells.

* **Chemokines:** These chemotactic factors, such as CCL3 and CCL4, attract other immune cells to the site of inflammation.

* **Leukotrienes:** These lipid mediators contribute to bronchoconstriction, vascular permeability, and inflammation.

* **Prostaglandins:** These lipid mediators contribute to pain, fever, and inflammation.

The specific composition of mast cell granules can vary depending on the tissue location and the type of mast cell. However, the overall function of these granules is to rapidly release a variety of mediators that contribute to allergic and inflammatory responses. This release is triggered by the binding of specific allergens or other stimuli to receptors on the surface of the mast cell.'
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Proteins (1)

Compounds (14)