mast cell : lecture note

 mast cell 

•       Mast cells contribute to homeostasis in the immune system.

•       They serve as a first line of defense against antigens entering the body due to their location in the skin and mucosa

•       Mast cells are especially important in the homeostasis of the commensal bacteria of the gut

 

•      Mast cell granules are metachromatic because of the high content of acidic radicals in the heparin glycosaminoglycan. Metachromasia is a property of certain molecules that changes the color of some basic aniline dyes (eg, toluidine blue). The structure containing the metachromatic molecules takes on a color (purple-red) different from that of the applied dye (blue).

•      Although they have similar morphology, there are at least two populations of mast cells in connective tissues. One type, called the connective tissue mast cell, is found in the skin and peritoneal cavity; these cells measure 10–12 µm in diameter and their granules contain the anticoagulant heparin. The second type, the so-called mucosal mast cell, is present in the connective tissue of the intestinal mucosa and in the lungs. These cells are smaller (only 5–10 µm) than the connective tissue mast cells and their granules contain chondroitin sulfate instead of heparin.

•       Difference between connective tissue mast cell and mucosal mast cell

Topics	connective tissue mast cell	mucosal mast cell
Another name	Also known as MCTC mast cell	Also known as MCT mast cell
Location	Skin , intestinal submucosa, breast and axillary lymph nodes	Lungs, intestinal mucosa
Granules and its internal structure	Granules with Lattice like internal structure	Granule with a scroll like internal structure
Granules contain	Tryptase and chymase	Only tryptase

However, mature mast cells are generally not thought to undergo cell division and are considered terminally differentiated. Occasionally cell division is occurred

The surface of mast cells contains Fc receptors for immunoglobulin E (IgE),

 a type of immunoglobulin produced by plasma cells. Most IgE molecules are bound

 to the surface of mast cells and blood basophils; very few remain in the plasma.

 

Mast cells originate from progenitor cells in the bone marrow. These progenitor cells circulate in the blood, cross the wall of venules and capillaries, and penetrate the tissues,