Immunohistochemical identification of tissue mast cells | | |
Tryptase | α/βI tryptase | Specific pan-mast cell marker |
| βII/βIII tryptase | Double IHC staining with chymase can be used to distinguish MCT and MCTC mast cells |
Chymase | CMA1 | Specific MCTC marker |
| | Double IHC staining with tryptase can be used to distinguish MCT and MCTC mast cells |
CPA3 | Carboxypeptidase A3 (CPA3), MC-CPA3 | Mast cell specific |
| | Primarily expressed in MCTC cells but CPA3 has also been identified in chymase-low mast cells |
CD117 | Mast/stem cell growth factor receptor (SCFR), c-KIT | A key, albeit nonspecific, marker for mast cells; also expressed on basophils and haematopoietic stem cells |
FcϵRI | High-affinity IgE receptor (FcϵRI) | Important but nonspecific marker for mast cells; also expressed on basophils and dendritic cells |
Identification of tissue mast cells by flow cytometry | | |
CD117 | Mast/stem cell growth factor receptor (SCFR), c-KIT | Gating of CD117-high cells with characteristic side scatter properties are commonly used to identify mast cells (apart from confounding expression on progenitor cells, invariable CD117 expression is also present on basophils) |
FcϵRI | High-affinity IgE receptor (FcϵRI) | FcϵRI positivity combined with CD117 expression and characteristic side scatter properties requires awareness of the low FcϵRI expression on human alveolar mast cells and confounding expression on basophils and dendritic cells |
Systemic markers of mast cell activation | | |
Histamine | 2-(1H-imidazol-4-yl) ethanamine | Limited use in respiratory diseases due to short-lived increase in plasma, also produced by basophils, nerves and enterochromaffin-like cells in the gut |
Tryptase | α/βI tryptase | |
| βII/βIII tryptase | Mast cell specific but limited assay sensitivity limits its use outside systemic anaphylactic reactions or mastocytosis |
CPA3 | Carboxypeptidase A3 (CPA3), MC-CPA3 | Mast cell specific, higher sensitivity than tryptase but CPA3 do not reflect the activity of MCT cells |
PGD2 | Prostaglandin D2 | Not mast cell specific, but mast cells contribute to the vast majority of plasma PGD2 |
| | Robust and sensitive detection of the PGD2 metabolite 9a11b-PGF2 has been measured in asthma by GC-NICIMS |