Mast cells are were first described by Paul Ehrlich (1879), as being cells that have prominent cytoplasmic granules
stained with basic dyes. Mast cells are found resident in tissues throughout the body, particularly in vicinity of
blood vessels and nerves. They are numerous under epithelial surfaces, e.g. in the respiratory and gastrointestinal
system, and skin, surfaces in intimate contact with microorganisms and allergens in the environment. Mast cells
originate from bone marrow stem cells, and enter to the circulation as progenitor cells and subsequently invade
into distinct tissues, where they differentiate into two main subtypes of mature mast cells. Proliferation,
migration, differentiation, and survive of mast cells are regulated by tissue-derived local factors including stem
cell factor. Mast cells are activated by a variety of physical, biological, and chemical stimuli. After activation,
mast cells can secrete mediators that either preformed or newly synthesized. Furthermore, mast cells are
important sources of many cytokines which effect inflammation, immunity, and other biological processes. Mast
cells have a clear and pivotal role in allergic reactions and parasite infections, but also take part in physiological
processes such as innate and acquired immunity, tissue repair, angiogenesis, coagulation and fibrinolysis.
Key Words: Mast cells, Heterogeneity, Physiological functions
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