Anaphylactic degranulation
| Mast cell | |
|---|---|
Mast cells
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| Details | |
| System | Immune system |
| Identifiers | |
| Latin | mastocytus |
| TH | H2.00.03.0.01010 |
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Anatomical terms of microanatomy []
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A mast cell (also known as a mastocyte or a labrocyte) is a type of white blood cell. Specifically, it is a type of granulocyte derived from the myeloid stem cell that is a part of the immune and neuroimmune systems and contains many granules rich in histamine and heparin. Although best known for their role in allergy and anaphylaxis, mast cells play an important protective role as well, being intimately involved in wound healing, angiogenesis, immune tolerance, defense against pathogens, and blood–brain barrier function.
The mast cell is very similar in both appearance and function to the basophil, another type of white blood cell. Although mast cells were once thought to be tissue resident basophils, it has been shown that the two cells develop from different hematopoietic lineages and thus cannot be the same cells.
Mast cells are very similar to basophil granulocytes (a class of white blood cells) in blood. Both are granulated cells that contain histamine and heparin, an anticoagulant. The Fc region of immunoglobulin E (IgE) becomes bound to mast cells and basophils and when IgE's paratopes bind to an antigen, it causes the cells to release histamine and other inflammatory mediators. These similarities have led many to speculate that mast cells are basophils that have "homed in" on tissues. Furthermore, they share a common precursor in bone marrow expressing the CD34 molecule. Basophils leave the bone marrow already mature, whereas the mast cell circulates in an immature form, only maturing once in a tissue site. The site an immature mast cell settles in probably determines its precise characteristics. The first in vitro differentiation and growth of a pure population of mouse mast cells has been carried out using conditioned medium derived from concanavalin A-stimulated splenocytes. Later, it was discovered that T cell-derived interleukin 3 was the component present in the conditioned media that was required for mast cell differentiation and growth.
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