A mast cell (or mastocyte) is a resident cell of areolar connective tissue (loose connective tissue) that 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 and defense against pathogens.

Mast cells are present in most tissues in the vicinity of blood vessels, and are especially prominent near the boundaries between the outside world and the internal milieu, such as the skin, mucosa of the lungs and digestive tract, as well as in the mouth, conjunctiva and nose.

Carboxypeptidase A

• a mast cell differentiation marker. PMID: 3680950

Chymase

• a mast cell marker. PMID: 9396359
• a neutral serine protease secreted from the mast cell. PMID: 9396359

CD25

• a reliable immunohistochemical marker for the discrimination of neoplastic from normal/reactive mast cells. PMID: 15371947

CD34

• a specific marker of mature murine mast cells. PMID: 12384153
• a 90- to 120-kDa cell surface sialomucin. PMID: 12384153

CD117 (c-Kit)

• a type III tyrosine kinase protein involved in mast cell growth and differentiation. PMID: 15586571
• three patterns of KIT expression: a cytoplasmic diffuse pattern, a membranous pattern with immunostaining located on the cell surface, and a cytoplasmic perinuclear pattern, where KIT expression was detected in the cytoplasm of the neoplastic mast cells, close to the nucleus. PMID: 15586571, PMID: 9596274
• CD117 expression is effective in the separation of mast cell disease from disorders that may simulate it histologically. PMID: 10632491
• expressed by a variety of normal human tissue cell types, including breast epithelium, germ cells, melanocytes, immature myeloid cells, and mast cells. PMID: 9596274

Fluorescent Berberine Binding

• a marker of secretory activity in mast cells. PMID: 6190761

Histamine

• a marker of mast cell activation. PMID: 1607547

Ki-MC1

• a useful marker for normal skin mast cells. PMID: 7577581

Ki-M1P

• primarily identifies immature mast cells and monocytes/macrophages. PMID: 7577581

LAMP-1/LAMP-2

• activation markers for normal mast cells. PMID: 15351990

Mast Cell Tryptase

• specific mast cell enzyme. PMID: 1607547
• a marker for the activation and localization of mast cells and almost exclusively expressed in mast cells. PMID: 10460298

PGD2

• a marker of mast cell activation. PMID: 10352758
• major cyclooxygenase metabolite of arachidonic acid released after stimulation of mast cells. PMID: 10352758, PMID: 15170023