Table 2.

Human mast cell markers and mast cell detection techniques

Markers	Cell type	Staining technique	Additionally stained structures	Notes
1. Sulfated glycosaminoglycans (including heparin)	Mature serosal mastocytes, a part of mucosal mastocytes	Toluidine blue Methylene blue Thionin Safranin O Basic brown Methylene green Azure A May-Grünwald–Giemsa	Macrophages, basophilic leukocytes, goblet cells, Clara cells	Toluidine blue and methylene blue staining is the easiest and most effective method to detect most mastocytes
2. Heparin	Mature serosal mastocytes	Berberine Avidin Acridine orange Immunohistochemistry	Basophilic leukocytes For avidin — any cells containing biotin	Berberine, avidin are highly selective markers of heparin, but berberine does not cause fluorescence in human skin mastocytes
3. Chondroitin sulfate Е	Mucosal and immature mastocytes	Alcian blue Astra blue	Components of connective tissue intercellular substance	Frequently used in combination with safranin O for simultaneous detection of mucous and serosal mastocytes
4. Tryptase	Serosal and mucosal mastocytes	Leder’s reaction Immunohistochemistry	None	Tryptase immunohistochemistry is the most effective technique to detect human mastocytes Leder’s reaction reveals an active enzyme alone
5. Chymase	Serosal mastocytes	Leder’s reaction Immunohistochemistry	None	Leder’s reaction reveals an active enzyme alone
6. c-kit (CD117)	Mastocytes	Immunohistochemistry	Stem cells, germinal cells, epithelial cells, interstitial cells of Cajal, melanocytes and basal skin cells, neurons, gliocytes	Also used as a tumor marker
7. Immunoglobulin receptor Е (FcεRI)	Mastocytes	Immunohistochemistry	Basophilic leukocytes, monocytes, eosinophils, epidermal Langerhans cells
8. Histamine	Mastocytes (primarily, serosal)	Immunohistochemistry Histochemistry	Some neurons, histamine-containing epithelial endocrine cells of the stomach, basophilic leukocytes, neutrophils, monocytes, macrophages, dendritic cells
9. Serotonin	Mastocytes (primarily, serosal)	Immunohistochemistry Histochemistry	Neurons, gustatory receptor cells, glomus cells of carotid bodies, enterochromaffin cells, trophoblast, decidual cells, keratinocytes, fibroblasts, melanocytes, platelets
10. Vascular endothelial growth factor receptor-1 (VEGFR-1)	Mastocytes	Immunohistochemistry	Endothelial vascular cells, epithelial cells of the uterus and bronchi, type 2 pneumocytes, cytotrophoblasts, interstitial cells of testicles, Т lymphocytes, monocytes, micro- and astroglia, neurons	Also used as a tumor marker

Note: the most effective markers for mast cell detection exhibiting the highest specificity are highlighted in bold; numbers 6–10 represent less selective mast cell markers, their usage can result in obtaining erroneous results.