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Signs, Symptoms & Triggers


Mast cells can be activated through both IgE and non-IgE-related mechanisms, resulting in the release of mediators, such as tryptase, histamine, heparin, leukotrienes and prostaglandins.1 This activation can occur in a healthy person, for example in response to a mosquito bite, and in patients with both mastocytosis and mast cell activation syndrome (MCAS). Patients with mastocytosis have extra mast cells that can activate and release their mediators, in addition to the possibility of mast cells that may more readily release mediators, resulting in increased mediator-induced symptoms. Patients with MCAS may also have mast cells that are signalled to release their mediators more easily; this may depend on genetics, tissue location of the reacting mast cells, the trigger that initiates the response, or even coexisting conditions.2, 3 Symptomatology can arise from both mediator release and/or from mast cell proliferation, accumulation and infiltration in tissues, depending on the form of mast cell disease. Triggers can be common to both patients with mastocytosis and MCAS, but may be different for each patient.


  1. Castells M. Mast cell mediators in allergic inflammation and mastocytosis. Immunol Allergy Clin North Am. 2006 Aug;26(3):465-85. http://www.ncbi.nlm.nih.gov/pubmed/16931289
  2. Akin C. Mast cell activation disorders. J Allergy Clin Immunol Pract. 2014 May-Jun;2(3):252-7 e1; quiz 8. http://www.ncbi.nlm.nih.gov/pubmed/24811013
  3. Valent P. Mast cell activation syndromes: definition and classification. Allergy. 2013 Apr;68(4):417-24. http://www.ncbi.nlm.nih.gov/pubmed/23409940


TAMS wish to acknowledge The Mast Cell Diseases Society (TMS) as the original authors of the above information. Reproduced with permission. View original source on the TMS website.

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