Page 964 - Veterinary Immunology, 10th Edition

VetBooks.ir Mast Cells

Mast cells play a key role in allergic diseases and innate immunity.
Because they are located close to body surfaces, they act as sentinel

cells and release inflammatory molecules immediately after
encountering invaders. They recognize PAMPs and damage-
associated molecular patterns (DAMPs) through their PRRs and in
response release the contents of their cytoplasmic granules within
minutes (Chapter 2). This release normally occurs in a controlled

manner and ensures that the severity and type of inflammation are
appropriate to the body's immediate needs— but not always!

Structure and Location

Mast cells are large, round cells (15–20 µm in diameter) scattered
throughout the body in connective tissue, under mucosal surfaces,
and around nerves (Fig. 29.6). They are found in greatest numbers
under the skin or in the intestine and airways. Because they are

located close to blood vessels, they can regulate blood flow and
influence cellular migration. They are easily recognizable because
their cytoplasm is densely packed with large granules that stain
strongly with dyes such as toluidine blue. These granules often

mask the large, bean-shaped nucleus (Fig. 29.7). (Mast cells are so-
called because, being full of granules, they were considered to be
“well-fed cells” [German Mastzellen].)

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