A mast cell is a type of white blood cell called a granulocyte. Mast cells are present in the conective tissues surrounding blood vessels and nerves, as well as at the barriers between the body's internal environment and the external one, including thelungs, digestive tract, nose, mouth and skin. They play an important role in the mucosal immune system and allergic response, as well as immune tolerance, defense against pathogens, and blood–brain barrier function.
When mast cells degranulate, they release histamine and heparin, an anticoagulant. Histamine causes endothelial cells lining blood vessels and lymphatic vessels to contract, weakening the junctions between these cells, and allowing proteins and cells from the plasma to leak through into the connective tissue.
Physiology[edit | edit source]
Degranulation[edit | edit source]
Sunshine[edit | edit source]
Inhibition[edit | edit source]
Vitamin C reduces blood histamine levels, potentially through several mechanisms: by inhibiting mast cell production; by increasing diamine oxidase (an enzyme that breaks down histamine); by inhibiting mast cell degranulation (and the release of histamine in the first place), and by inhibiting histidine decarboxylase (the enzyme that forms histamine). Vitamin B6 is also a diamine oxidase cofactor.
Infection[edit | edit source]
In a mouse model of myocarditis, Coxsackievirus infection was found to upregulate Toll-like receptor 4 on mast cells and macrophages immediately following infection. It also increased numbers of mast cells.
Nervous system[edit | edit source]
Mast cells play an important role in the gut-brain axis of the peripheral nervous system. They are found throughout the gastrointestinal tract near sensory nerve fibers, such as the sensory vagus nerve. In the central nervous system, they are found on the blood-brain barrier, in the dural layer of the meninges, and in areas of the brain responsible for pain or neuroendocrine functions including the pituitary stalk, pineal gland, thalamus, and hypothalamus.
Role in human disease[edit | edit source]
Mast cell activation disorder[edit | edit source]
See full article: Mast cell activation disorder
Mast cell activation disorder (MCAD) is a disorder where mast cells are normal in number but over-responsive to dietary and environmental triggers. Cells release excess histamine and other signaling molecules, causing symptoms. It is often found in patients with Ehlers-Danlos syndrome (EDS) and postural orthostatic tachycardia syndrome (POTS), a form of orthostatic intolerance, two conditions commonly co-morbid with ME/CFS. The overlap between EDS, POTS, and MCAD is thought to be due to increased tryptase production owing to an extra copy of a gene called TPSAB1.
MCAD should be distinguished from mastocytosis, a genetic disorder of excessive populations of mast cells.
Chronic fatigue syndrome[edit | edit source]
One study found that moderate and severe ME/CFS patients had higher levels of naive mast cells than healthy controls. Clinicians increasingly believe that mast cells underly the dysfunction found in the disease.
Fibromyalgia[edit | edit source]
Ehlers Danlos Syndrome[edit | edit source]
Postural orthostatic tachycardia[edit | edit source]
Notable studies[edit | edit source]
- 2016, Novel characterisation of mast cell phenotypes from peripheral blood mononuclear cells in chronic fatigue syndrome/myalgic encephalomyelitis patients (Donald Staines, Sonya Marshall-Gradisnik)
References[edit | edit source]
- "Connective Tissue: Macrophages, Mast cells and Plasma cells". The Histology Guide. Retrieved April 22, 2018.
- Mio, M (1999). "Ultraviolet B (UVB) light-induced histamine release from rat peritoneal mast cells and its augmentation by certain phenothiazine compounds". Immunopharmacology.
- Clemetson, C. A. (April 1980), "Histamine and ascorbic acid in human blood", The Journal of Nutrition, 110 (4): 662–668, ISSN 0022-3166, PMID 7365537
- Johnston, C. S.; Martin, L. J.; Cai, X. (April 1992), "Antihistamine effect of supplemental ascorbic acid and neutrophil chemotaxis", Journal of the American College of Nutrition, 11 (2): 172–176, ISSN 0731-5724, PMID 1578094
- Johnston, CS (December 1996). "Vitamin C depletion is associated with alterations in blood histamine and plasma free carnitine in adults". J Am Coll Nutr.
- Molderings, Gerhard (2016). "Pharmacological treatment options for mast cell activation disease". Naunyn Schmiedebergs Arch Pharmacol.
- Fairweather, D (2005). "Viruses as adjuvants for autoimmunity: evidence from Coxsackievirus-induced myocarditis". Rev Med Virol.
- Milner, Joshua, Dr. "Research Update: POTS, EDS, MCAS Genetics." 2015 Dysautonomia International Conference & CME. Washington DC. Dysautonomia International Research Update: POTS, EDS, MCAS Genetics. Web. <https://vimeo.com/142039306>.
- Horowitz, Kate (October 17, 2016). "One Gene Mutation Links Three Mysterious, Debilitating Diseases". Mental Floss. Retrieved April 22, 2018.
- Cheung, Ingrid (February 2015). "A New Disease Cluster: Mast Cell Activation Syndrome, Postural Orthostatic Tachycardia Syndrome, and Ehlers-Danlos Syndrome". The Journal of Allergy and Clinical Immunology.
- Nguyen, T (June 2017). "Novel characterisation of mast cell phenotypes from peripheral blood mononuclear cells in chronic fatigue syndrome/myalgic encephalomyelitis patients". Asian Pacific Journal of Allergy and Immunology.
- Tucker, Miriam (March 13, 2018). "Mast Cell Activation May Underlie 'Chronic Fatigue Syndrome'". Medscape. Retrieved April 22, 2018.