A mast cell (also known as a mastocyte) is a type of white blood cell. Specifically, it is a type of granulocyte derived from the myeloid stem cell that is a part of the immune and neuroimmune systems and 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, angiogenesis, immune tolerance, defense against pathogens, and blood–brain barrier function.
The mast cell is very similar in both appearance and function to the basophil, another type of white blood cell. Although mast cells were once thought to be tissue resident basophils, it has been shown that the two cells develop from different hematopoietic lineages and thus cannot be the same cells.
Neuroendocrinology of mast cells: Challenges and Controversies. 2017
Mast cells are located perivascularly and express numerous receptors for diverse ligands such as allergens, pathogens, neurotransmitters, neuropeptides and hormones including acetylcholine, calcitonin gene-related peptide (CGRP), corticosteroids, corticotropin-releasing hormone (CRH), β-endorphin, epinephrine, 17β-estradiol, gonadotrophins, hemokinin-A (HKA), leptin, melatonin, neurotensin (NT), parathyroid hormone (PTH), substance P (SP) and vasoactive instestinal peptide (VIP).
Mast cells maturation
Mast Cells | Musculoskeletal KeyMast cells originate from multipotent hematopoietic stem cells in the bone marrow and mature in peripheral tissues, rather than the marrow. Immature progenitors enter the blood, migrate to tissues, and differentiate into mature mast cells under the influence of Stem Cell Factor (SCF) interacting with the KIT receptor.
Key Aspects of Mast Cell Maturation:
Developmental Pathway: Hematopoietic Stem Cells (HSCs)
Committed Mast Cell Progenitors (MCPs)
Migration in Blood
Tissue Infiltration
Differentiation (Mature Mast Cells).
Final Differentiation Location: Progenitors mature locally within tissues, particularly mucosal and connective tissues, influenced by the microenvironment.
Key Growth Factor (KIT Ligand/SCF): The interaction between the KIT receptor on the cell and SCF (Stem Cell Factor) is crucial for the proliferation, maturation, and survival of mast cells.
Maturation Markers: Mature mast cells are characterized by high expression of the receptor tyrosine kinase KIT (CD117), FcεRI (high-affinity IgE receptor), and the acquisition of metachromatic cytoplasmic granules filled with mediators like histamine.
Types of Mature Mast Cells:
Connective tissue-type mast cells (CTMCs): Typically found in skin and intestinal submucosa, often containing chymase, tryptase, and carboxypeptidase.
Mucosal mast cells (MMCs): Found in the respiratory and intestinal mucosa, often containing primarily tryptase.
Regulation: Mast cell maturation is regulated by various factors including Wnt-
-catenin signaling and granule-related factors such as histamine.
Unlike many other myeloid cells, mature mast cells can maintain a degree of proliferative potential and do not normally circulate in their mature form.
