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mast cell disease

Mast cells in vascular disease: Part 2

Chymase is a mediator produced and released by mast cells. It is an enzyme that converts angiotensin I to angiotensin II, which is important in regulating blood pressure. Chymase can also activate TGF-b1, IL-1b and degrade some of the proteins that hold cells together in tissues.

Release of chymase by local mast cells is a large factor in plaque instability. This is thought to be by raising amount of angiotensin II and degrading a structure that stabilizes the plaque. Chymase also causes apoptosis, or cell death, of smooth muscle cells, which lie underneath the plaque. It was recently discovered that activation of the toll like receptor 4 (TLR4) on the surface of the mast cell causes the mast cell to release IL-6. IL-6 then binds to the mast cell and causes it to make and release chymase.

Chymase and tryptase also interfere with cholesterol transport. In plaques, macrophages eat cholesterol and become foam cells. When the foam cells try to release the cholesterol, chymase and tryptase can prevent this, which stabilizes the plaque and makes it larger.

Mast cell activation is also known to affect plaque behavior. In mast cells that could not be activated by IgE, the size of the plaque and cell death around it were reduced. IgE levels are higher in patients who suffer acute coronary syndromes compared with those who don’t, with IgE levels peaking seven days after the event. Patients with hyper-IgE syndrome are much more likely to have coronary artery dilation or aneurysm, although atherosclerosis was not common. A whole body MRI detected impaired vascular integrity in these patients. These patients are expected to be more prone to mast cell activation.

In mastocytosis patients, no increase in atherosclerosis has been reported, though cardiovascular symptoms are not unusual. Some mastocytosis patients demonstrate vascular instability. Two cases of strokes due to cranial artery dissection have been published.

Mice that lack substance P, a neuropeptide that activates mast cells, have better cardiac function than expected. In mouse models, adding substance P to a plaque could cause hemorrhage only if the mouse had mast cells. This indicates that mast cell activation is important in plaque rupture.



Simon Kennedy, Junxi Wu, Roger M. Wadsworth, Catherine E. Lawrence, Pasquale Maffia. Mast cells and vascular diseases. Pharmacology & Therapeutics 138 (2013) 53–65.

Ramalho, L. S., Oliveira, L. F., Cavellani, C. L., Ferraz, M. L., de Oliveira, F. A., Miranda Corrêa, R. R., et al. (2012). Role of mast cell chymase and tryptase in the progression of atherosclerosis: study in 44 autopsied cases. Ann Diagn Pathol 17, 28–31.

Meléndez, G. C., Li, J., Law, B. A., Janicki, J. S., Supowit, S. C., & Levick, S. P. (2011). Substance P induces adverse myocardial remodelling via a mechanism involving cardiac mast cells. Cardiovasc Res 92, 420–429.

Guo, T., Chen,W. Q., Zhang, C., Zhao, Y. X., & Zhang, Y. (2009). Chymase activity is closely related with plaque vulnerability in a hamster model of atherosclerosis. Atherosclerosis 207, 59–67.


What do all these words mean? (Part 2)

What does it mean if a person is CD117 positive in a biopsy? Is this bad?

In the context of mast cell disease, it usually just means that mast cells were found.


If CD117 is normal for mast cells, why are people sometimes “negative for CD117” on biopsies?

This sometimes happens. When you have mast cell disease, you often have more CD117 receptors on mast cells. This makes it easier for the test to find them. So when you are found to be “negative for CD117” in regards to mast cell disease, you are not truly “negative”. You just express a lower amount of CD117 receptors so the test didn’t see them.


I am a mast cell patient and my bone marrow biopsy was positive for CD117. How do I know that it is normal mast cells that show CD117 and not these other dangerous cells you mentioned?

You can tell by looking at the cells with special stains. Pathologists and immunohistochemistry scientists are very skilled at distinguishing one cell type from another. They can tell based upon what the cell looks like in addition to being positive for CD117.


If I am CD117 positive in a biopsy, does that mean I am “CKIT positive”?

No. If I could do away with one single phrase in mast cell terminology, it would be CKIT+.

CKIT+ is a term used to mean “positive for the D816V mutation in codon 816 of the CKIT gene”. It means you are positive for a mutation that has been associated with neoplastic disorders of mast cells. So when people say they are CKIT+, they mean they were found to have a mutation. They do NOT mean they were found to have CKIT/CD117 on their mast cell surfaces, because this is totally normal and is the case for everyone.

Additionally, the test to detect CD117 on a cell surface is NOT the same test used to identify the D816V mutation. That test breaks open the cells and looks for a specific mutation in the DNA sequence. They are not run at the same time.


Why is it important to know if I am positive for the D816V mutation (CKIT+)?

The D816V mutation changes the shape of the CKIT receptor. Due to this wrong shape, the receptor does not need SCF to bind to the receptor to tell the mast cell to live longer. In this new shape, the receptor is stuck in an “activated” position, so it is telling the cell to live longer all the time, without SCF. This is called “autoactivation”.

The D816V mutation is one of the minor criteria for systemic mastocytosis, so it is important for classification purposes. Also, it may affect your treatment plan in the unlikely situation of needing chemotherapy.


What is CD25?

CD25 is part of a receptor for a molecule called IL-2. Normally, mast cells do not express receptors for IL-2, which is a molecule that regulates development of T cells. When mast cells express CD25, it is an indication that the mast cell is neoplastic. Many T cells normally express CD25, so if it is on a biopsy report, keep in mind that it’s abnormal on mast cells, but not everywhere.

Presence of CD25 on mast cells is one of the minor criteria for SM.


What is CD2?

CD2 is an example of a “CD” molecule that is not a receptor. It is a cell adhesion molecule so it helps cells stick together. Normally, mast cells do not express CD2. When mast cells express CD2, it is an indication that the mast cell is neoplastic. Many T cells normally express CD25, so if it is on a biopsy report, keep in mind that it’s abnormal on mast cells, but not everywhere. CD2 is a less accurate indication of SM than CD25.

Presence of CD2 on mast cells is one of the minor criteria for SM.


What is CD30?

CD30 is a receptor for proteins associated with tumor necrosis factor. It is commonly referred to as a tumor marker, but this is not always the case. CD30 has recently been shown to be frequently positive in patients with all forms of SM (ISM, SSM, SM-AHNMD, ASM). However, on other cells besides mast cells, it may indicate lymphoma or other conditions.


What is CD34?

CD34 is another cell adhesion molecule. It is thought to allow stem cells to attach to proteins in the bone marrow. It is found on many progenitor cells, cells that later become other kinds of cells. Mast cells express CD34, though this tends to be lost as they move into tissues.

Mast cells in nerve pain

Mast cells are heavily involved in the generation and sensation of pain. The role of mast cells in neurogenic pain (also called nerve pain or neuropathy) is well established and is responsible for a number of painful conditions.

Pain is transmitted like this:

  1. You first feel the pain in nerve endings called nociceptors.
  2. These nerve endings and capillaries in the nearby tissue form a “pain unit” that sends pain signals.
  3. Mast cells are often found close to these nerve endings and capillaries. They release mediators like prostaglandins, histamine and bradykinin.
  4. Nociceptors release mediators like substance P, VIP and CRH, which activate mast cells.
  5. Mast cells then release mediators that increase permeability of the vessels and sensitize the nociceptors. This cycle, in which the nerve endings activate mast cells and the mast cells activate the nerve endings, is called a positive feed back loop. The end result is neurogenic inflammation, or inflammation caused by nerves.

Mast cells can communicate with nerve endings in a number of ways. The first way is by releasing mediators, which may bind to receptors on the nerve cells. A second way is by mast cells sticking to nerve cells through molecules like CADM-1 and N-cadherin; they are able to send signals when their membranes are touching. A third way is by the nerve cells ingesting mediators released by mast cells. These mediators are then transported to other nerve cells, where it can affect which genes are turned on and used.

Mast cells also draw other immune cells to the site of inflammation, like neutrophils and T cells. These cells also release mediators that increase pain, forming another positive feedback loop. The result is that inflammation can spread beyond the initial site of pain, causing a secondary, larger pain response. Hyperalgesia is an exaggerated pain response that is more severe than expected based upon the injury. Mast cells are thought to be directly involved in hyperalgesia and histamine is thought to cause this heightened pain sensation.

Chronic pain has been associated with mast cell degranulation. Degranulation close to colonic nerves is correlated with abdominal pain in IBS patients. Tryptase and histamine can also activate enteric nerves, causing the nerves to be oversensitive. Esophageal pain is also a function of mast cell degranulation.

The specific mechanism of bladder pain due to interstitial cystitis is not clear. However, mast cells are often elevated in IC patients, and contribute to inflammation. It is thought that activation of bladder nerves causes release of substance P by local nerve endings, which activates mast cells.

Overly sensitive and painful skin is sometimes a function of mast cells as well. A significant increase in mast cells has been found in the dermis of fibromyalgia patients. Chronic granulomatous inflammation of the skin causing pain has also been found to be from degranulation of mast cells.



Heron, Anne, Dubayle, David. 2013. A focus on mast cells and pain. Journal of Neuroimmunology 264 (2013) 1–7.

Parada, C.A., Tambeli, C.H., Cunha, F.Q., Ferreira, S.H., 2001. The major role of peripheral release of histamine and 5-hydroxytryptamine in formalin-induced nociception. Neuroscience 102, 937–944.

Theoharides, T.C., Kempuraj, D., Sant, G.R., 2001. Mast cell involvement in interstitial cystitis: a review of human and experimental evidence. Urology 57, 47–55.

Theoharides, T.C., Donelan, J., Kandere-Grzybowska, K., Konstantinidou, A., 2005. The role of mast cells in migraine pathophysiology. Brain Res. Brain Res. Rev. 49, 65–76.

Gao, G., Ouyang, A., Kaufman, M.P., Yu, S., 2011. ERK1/2 signaling pathway in mast cell activation-induced sensitization of esophageal nodose C-fiber neurons. Dis. Esophagus 24, 194–203.

Mast cells in vascular disease: Part 1

Atherosclerosis is a very specific type of artery hardening that occurs due to accumulation of white blood cells and their inflammation of the vessel. Atherosclerosis can cause heart attacks, formation of blood clots and obstruction of major vessels. There are a number of risk factors, including tobacco smoking, high LDL cholesterol, diabetes, vitamin B6 deficiency, high C reactive protein, and many others.

Atherosclerosis is now known to be an immunoinflammatory condition, one which results from inflammation mediated by immune cells. In recent years, mast cells have been found to play an important role in the formation of atherosclerotic lesions, progression and destabilization of the lesion, which in turn causes the more significant clinical effects. In 2004, 66% of men and 47% of women in the US had heart attack or sudden cardiac death as their first symptom of atherosclerotic heart disease.

Endothelial cells line the blood vessels and form the endothelium. In atherosclerotic plaques, monocytes from the blood burrow into the endothelium. They turn into macrophages, a different kind of cell. These macrophages eat certain kinds of cholesterol and start a cycle in inflammation in the vessel wall. Platelets then stick to the inflamed places.

Mast cells are known to have a number of behaviors that affect plaque pathology. Mast cells near plaques release tryptase, which activates endothelial cells through the PAR-2 receptor. This causes a series of events that produces platelet activating factor (PAF). PAF increases the permeability and contraction of the nearby smooth muscle, which can lead to vascular events.

Increased densities of mast cells have been found in the tissue layer overlaying plaques that ruptured. It has been hypothesized that mast cell released histamine could cause coronary spasm, making the plaque more likely to rupture. In a study that looked at 44 autopsy samples of aorta with atherosclerotic lesions, there was a direct correlation found between levels of tryptase and chymase, the amount of collagen in the plaque, and the size of the endothelium involved.

Mast cells that store basic fibroblast growth factor (bFGF) are found in small vessels inside plaques. Histamine may cause leakage from those tiny vessels, which can further make the plaque more likely to rupture.   In histamine deficient mice, the plaque area was reduced in size, and expression of genes for NF-kB, matrix metalloproteinases (MMPs), and inflammatory cytokines involved in plaque progression. Histamine is also involved in acute coronary vasospasm that may result in heart attack; this is called Kounis Syndrome.



Simon Kennedy, Junxi Wu, Roger M. Wadsworth, Catherine E. Lawrence, Pasquale Maffia. Mast cells and vascular diseases. Pharmacology & Therapeutics 138 (2013) 53–65.

Ramalho, L. S., Oliveira, L. F., Cavellani, C. L., Ferraz, M. L., de Oliveira, F. A., Miranda Corrêa, R. R., et al. (2012). Role of mast cell chymase and tryptase in the progression of atherosclerosis: study in 44 autopsied cases. Ann Diagn Pathol 17, 28–31.

Lappalainen,H., Laine, P., Pentikäinen,M. O., Sajantila,A.,& Kovanen, P. T. (2004).Mast cells in neovascularized human coronary plaques store and secrete basic fibroblast growth factor, a potent angiogenic mediator. Arterioscler Thromb Vasc Biol 24, 1880–1885.

Kounis, N. G., Mazarakis, A., Tsigkas, G., Giannopoulos, S., & Goudevenos, J. (2011). Kounis syndrome: a new twist on an old disease. Future Cardiol 7, 805–824.

Effects of Platelet Activating Factor (PAF) in asthma and anaphylaxis

PAF is released by many different cells, including eosinophils, mast cells, neutrophils, monocytes, macrophages and endothelial cells. PAF receptors are expressed by platelets, monocytes, mast cells, neutrophils, and eosinophils. T and B cells do not express PAF receptors, but PAF can stimulate them to migration of these cells. PAF receptors are found to be increased in eosinophils of asthma patients. PAF receptors are also elevated in lungs of asthmatic patients. PAF can activate mast cells and basophils, causing histamine release. One study proposed the PAF activation of basophils may play a role in aspirin sensitivity in asthma patients.

PAF is most well known for its effects on the airway. It causes constriction of the airway and can affect the way oxygen is brought into the lungs. However, it also has many other effects in the body, many of which affect anaphylaxis and severity thereof.

PAF activates eosinophils and neutrophils to degranulate. It also causes leukotriene C4 production by activated eosinophils in asthma patients, but not in normal patients. A PAF inhibitor has been observed to prevent eosinophil migration and leukotriene C4. Another PAF inhibitor was able to inhibit eosinophil activation by PAF. In activated neutrophils in asthma patients, PAF causes an increase in secretion of leukotriene B4 and increased 5-lipoxygenase activity.

PAF is a powerful signal for eosinophils to migrate toward the cell releasing PAF, and may be involved in inflammation resulting in eosinophilic infiltration. PAF can cause eosinophilic movement across endothelium and into airway. This behavior is increased during asthma attacks and can be minimized with steroids.

PAF injected into the skin causes a biphasic reaction with immediate hiving, then a delayed redness and pain reaction that causes eosinophilic infiltration. PAF also increases IL-6 production by macrophages, activates IL-4 production by T cells, and enhances IL-6 production by mononuclear cells in peripheral blood.

PAF has been heavily linked to asthma. One study found higher levels of PAF as well as lower level of the enzyme that inactivates PAF in plasma of asthmatic adults both during attacks and the rest of the time. When exposed to allergens, PAF level in blood rapidly increases. The large increases in PAF level upon exposure were ameliorated upon successful allergen immunotherapy (also known in the US as “allergy shots”).

PAF induced bronchoconstriction does not affect histamine release and is not alleviated by H1 receptor antihistamines. Inhaling PAF does not change plasma histamine level in asthmatics. Leukotrienes may behave as secondary mediators of PAF action. Zileuton attenuated systemic and respiratory effects of PAF, including airway constriction and changes in neutrophil behavior.

PAF level, and the level of the enzyme that metabolizes it, PAF-acetylhydrolase, is directly correlated to severity of anaphylaxis. Patients with grade I anaphylaxis have 2.5x as much PAF as controls; grade II, 5x; and grade III, 10x. PAF blockers are being investigated for use in this context. Rupatadine is available in some countries, and has H1 antihistamine and PAF blocking activity.

The exact nature of PAF’s activity in anaphylaxis is unclear. It has been shown to cause mast cell degranulation and increased production and release of prostaglandin D2. It can also amplify the response to IgE, making the allergic reaction worse. However, these effects were not seen in skin mast cells for unknown reasons. The source of PAF that acts on mast cells in anaphylaxis is unknown, but is thought to be at least partially from mast cells themselves.



Kasperska-Zajac, Z. Brzoza, and B. Rogala. Platelet Activating Factor as a Mediator and Therapeutic Approach in Bronchial Asthma. Inflammation, Vol. 31, No. 2, April 2008.

Peter Vadas, M.D., Ph.D., Milton Gold, M.D., Boris Perelman, Ph.D., Gary M. Liss, M.D., Gideon Lack, M.D., Thomas Blyth, M.D., F. Estelle R. Simons, M.D., Keith J. Simons, Ph.D., Dan Cass, M.D., and Jupiter Yeung, Ph.D. Platelet-Activating Factor, PAF Acetylhydrolase, and Severe Anaphylaxis. N Engl J Med 2008; 358:28-35.

Vadas P, Gold M, Liss G, Smith C, Yeung J, Perelman B. PAF acetylhydrolase predisposes to fatal anaphylaxis. J Allergy Clin Immunol 2003;111: S206-S206.

Kajiwara N, Sasaki T, Bradding P, Cruse G, Sagara H, Ohmori K, Saito H, Ra C, Okayama Y. Activation of human mast cells through the platelet-activating factor receptor. J Allergy Clin Immunol. 2010 May; 125(5): 1137-1145.

Circadian rhythm of mast cells

The circadian clock (also called circadian rhythm) regulates many physiological activities including the sleep-wake cycle, metabolism, digestion and immune processes. It is essentially a system that tells cells in the body what to do based on a 24 hour cycle, which can be influenced by such things as light cues, sleep and medication. Many cell types in the body have been shown to maintain their own internal circadian clocks and to change their behavior based upon time. Mast cells and eosinophils have been shown to maintain their own internal clocks.

On a cellular level, the circadian clock is maintained by the expression of clock genes. Inside the cell, a protein called CLOCK attaches to another protein (BMAL1) and they initiate expression of several genes that regulate circadian rhythm in the cell. These genes are called Period 1, Period 2, Period 3, Cryptochrome 1 and Cryptochrome 2. The proteins made by those genes regulate the expression of other genes based upon time.

An interesting facet of allergic disease is the well established variation in symptom severity depending on the time of day. This is seen in a variety of allergic conditions, such as asthma and atopic dermatitis. Allergic symptoms, including those that affect pulmonary function, are worse between midnight and morning, with a ramping up of symptoms seen around 10pm. This worsening overnight often results in sleep disruptions and “morning attacks”, which affect rest and result in decreased quality of life for patients. This has been verified repeatedly both through mouse studies and in reports of human patients.

Circadian rhythm has been shown to affect mediator release in mast cells, and this has been shown to be regulated by the five genes listed above. If even one of those genes are mutated, the mediator release becomes uniform and does not shown the peaks and lows observed normally. Both tryptase and plasma histamine levels have been observed to have lower levels in the afternoon and to peak at night. A marker associated with degranulation (b-hexosaminidase) showed the same pattern.

There is currently no information available on how mast cells tell time in relation to the rest of the body, though it is thought that mast cells receive molecular signals that “start the clock”. Importantly, in mice that have had their adrenal glands removed, mast cells do not shown circadian rhythms in mediator release. This indicates that the signal that “starts the clock” comes to mast cells from the adrenal glands. Corticosterone is being investigated as the possible signal, as it has been shown to induce expression of at least two clock genes, Period 1 and Period 2.



Silver, A.C., Arjona, A., Hughes, M.E., Nitabach, M.N., Fikrig, E., 2012. Circadian expres-sion of clock genes in mouse macrophages, dendritic cells, and B cells. BrainBehav. Immun. 3, 407–413.

Smolensky, M.H., Lemmer, B., Reinberg, A.E., 2007. Chronobiology and chronother-apy of allergic rhinitis and bronchial asthma. Adv. Drug Deliv. Rev. 9–10,852–882.

Baumann, A., Gonnenwein, S., Bischoff, S.C., Sherman, H., Chapnik, N., Froy, O.,Lorentz, A., 2013. The circadian clock is functional in eosinophils and mast cells. Immunology 4, 465–474.

Burioka, N., Fukuoka, Y., Koyanagi, S., Miyata, M., Takata, M., Chikumi, H., Takane, H.,Watanabe, M., Endo, M., Sako, T., Suyama, H., Ohdo, S., Shimizu, E., 2010. Asthma: chronopharmacotherapy and the molecular clock. Adv. Drug Deliv. Rev. 9–10,946–955.

Cermakian, N., Lange, T., Golombek, D., Sarkar, D., Nakao, A., Shibata, S., Mazzoccoli, G., 2013. Crosstalk between the circadian clock circuitry and the immune system.Chronobiol. Int. 7, 870–888.

IgE-dependent activation of human mast cells and fMLP-mediatedactivation of human eosinophils is controlled by the circadian clockAnja Baumanna, Katharina Feilhauerb, Stephan C. Bischoffa, Oren Froyc, Axel Lorentza. Molecular Immunology 64 (2015) 76–81.

Yuki Nakamura, et al. Circadian regulation of allergic reactions by the mast cell clock in mice. J Allergy Clin Immunol 133 (2014) 568-575.


Mast cell inhibitory effects of some microorganisms

We have talked recently about how infections can activate mast cells and result in worsening of symptoms in mast cell patients. However, some organisms are actually able to decrease mast cell degranulation and secretion of mediators. Some of these organisms are highly pathogenic with dangerous infectious capabilities, but some are commensal bacteria that can be found in probiotics. These findings support a growing body of evidence that indicates that the changes in our commensal organisms in the last thirty years have contributed to the increased frequency of atopic disease in developed countries. Additionally, improved hygiene and public health have decreased the frequency of some infections, which may also contribute to allergic conditions.

Lactobacillus and Bifidobacteria have been found to directly inhibit mast cell degranulation. Lactobacillus reduces both mast cell degranulation and cytokine secretion by reducing the number of IgE receptors on mast cell surface. Expression of IL-8 and TNF-a are actively decreased, while expression of the anti-inflammatory IL-10 is increased. Bifidobacterium bifidum inhibit IgE activation of mast cells in similar ways.

Salmonella typhimurium is a frequent cause of foodborne illness. In the US, it is estimated to cause 1,000,000 illness events annually, resulting in 19,000 hospitalizations and 380 deaths. It causes diarrhea, fever and severe abdominal cramping that can last several days. A 2001 study found that Salmonella are able to avoid detection by neutrophils through inactivation of local mast cells. Specifically, Salmonella inject a protein known as SptP into the fluid inside mast cells. Following exposure to Salmonella, mast cells lost their ability to degranulate, even when exposed to IgE or strong antigens.

Yersinia pestis, which causes plague, can also suppress mast cell degranulation by injecting a similar protein called YopH. Several forms of commensal E. coli (which do not cause infection) have been found to exhibit similar suppression.

Some organisms can cause mast cells to lyse (burst) and thus die. Pseudomonas aeruginosa releases exotoxin A, which causes lysis of mast cells.

Infectious fungi, such as Aspergillus fumigatus, release a gliotoxin that suppresses mast cell degranulation as well as mediator secretion. Other fungal products that decrease mast cell activity include FK-506 from Streptomyces tsukubaensis and cyclosporine A from Tolypocladium inflatum. Cyclosporine A is often used as an immunosuppressive after organ transplant and also sees some use in treating inflammatory disorders.

Some nematodes (roundworms) are also able to block mast cell degranulation. Filarial nematodes release a molecule, ES-62, that blocks IgE activation of mast cells as well as inhibiting secretion of allergic inflammatory factors. This finding is notable as it provides a possible reason why allergic diseases occur less frequently in developing countries. Toxoplasma gondii, a parasitic protozoan that causes toxoplasmosis, also prevented mast cell degranulation.



Choi, H.W., Brooking-Dixon, R., Neupane, S., Lee, C.-J., Miao, E.A., Staats, H.F., Abraham, S.N., 2013. Salmonella typhimurium impedes innate immunity with a mast-cell-suppressing protein tyrosine phosphatase, SptP. Immunity 39,1108–1120.

Cornelis, G.R., 2002. Yersinia type III secretion: send in the effectors. J. Cell Biol. 158, 401–408.

Magerl, M., Lammel, V., Siebenhaar, F., Zuberbier, T., Metz, M., Maurer, M., 2008. Non-pathogenic commensal Escherichia coli bacteria can inhibit degranulation of mast cells. Exp. Dermatol. 17, 427–435.

Harata, G., He, F., Takahashi, K., Hosono, A., Kawase, M., Kubota, A., Hiramatsu, M.,Kaminogawa, S., 2010. Bifidobacterium suppresses IgE-mediated degranulationof rat basophilic leukemia (RBL-2H3) cells. Microbiol. Immunol. 54, 54–57.

Forsythe, P., Wang, B., Khambati, I., Kunze, W.A., 2012. Systemic effects of ingested Lactobacillus rhamnosus: inhibition of mast cell membrane potassium (IKCa)current and degranulation. PLoS One 7, e41234.

Oksaharju, A., Kankainen, M., Kekkonen, R.A., Lindstedt, K.A., Kovanen, P.T., Korpela,R., Miettinen, M., 2011. Probiotic Lactobacillus rhamnosus downregulates FCER1and HRH4 expression in human mast cells. World J. Gastroenterol. 17, 750–759.

Wesolowski, J., Paumet, F., 2011. The impact of bacterial infection on mast celldegranulation. Immunol. Res. 51, 215–226.

Niide, O., Suzuki, Y., Yoshimaru, T., Inoue, T., Takayama, T., Ra, C., 2006. Fungal metabolite gliotoxin blocks mast cell activation by a calcium- and superoxide-dependent mechanism: implications for immunosuppressive activities. Clin.Immunol. 118, 108–116.

Melendez, A.J., Harnett, M.M., Pushparaj, P.N., Wong, W.S., Tay, H.K., McSharry, C.P.,Harnett, W., 2007. Inhibition of Fc epsilon RI-mediated mast cell responses by ES-62, a product of parasitic filarial nematodes. Nat. Med. 13, 1375–1381.

Hae Woong Choi, Soman N. Abraham. Mast cell mediator responses and their suppression by pathogenic and commensal microorganisms. Molecular Immunology 63 (2015) 74–79.

Initial diagnosis and treatment of mast cell activation disease: General notes for guidance

Mast cell disease is becoming more well known among both the public and medical providers, but there is still a lot of confusion regarding exactly what it is, how to diagnose and how to treat.

There are several tests that should be used when working up a patient for mast cell disease. Tryptase is the most well known of these tests, due to over 85% of patients with systemic mastocytosis (SM), a form of mast cell disease, having elevated tryptase. However, tryptase can be normal in mast cell patients, or may only be elevated during times of severe symptoms or anaphylaxis. While an elevated baseline tryptase can be used as confirmation for a mast cell disease (in the absence of frank hematologic disease), a normal tryptase test should not be used to discard the possibility of mast cell disease.

24-hour urine tests for mast cell mediators are most likely to capture evidence of mast cell activation when executed correctly. These tests measure n-methylhistamine, a metabolite of histamine, and prostaglandins D2 and F2a, which are all released by mast cells. Urine collected for this test should be kept refrigerated or on ice during collection and transport to the lab. I STRONGLY recommend communicating with the lab prior to beginning to this test to be sure that they understand the temperature requirements. The molecules being tested are not stable at room temperature and inappropriate storage can result in a negative test result in a positive patient. (For details on this topic and specific recommendations for testing, please refer to Afrin 2013).

Some providers also find utility in the measurement of other less specific mediators. Please refer to my previous post on this topic:

Due to the well established time sensitive nature of these tests (Afrin 2013), a patient who presents a “mast cell clinical picture” and responds to typical mast cell medications may in fact have mast cell disease in the presence of negative tests.

Depending on the clinical picture, a provider may feel it necessary to order a bone marrow biopsy, skin biopsy or biopsy of another organ to determine if mast cell infiltrates are present. This is not always immediately done in the presence of positive tryptase, n-methylhistamine, D2 prostaglandin or F2a prostaglandin test and will not always affect treatment. It is common knowledge among mast cell fluent providers that a negative biopsy does not exclude mast cell disease, but it is instead used to rule in the presence of specific proliferative entities like systemic mastocytosis (Picard 2013, Molderings 2011). Furthermore, a single biopsy may fail to capture a positive specimen in a known-positive patient (Butterfield 2004).

For more specific details regarding differentiation among the diagnostic categories of mast cell disease, please refer to my previous post on this topic:

There are a number of well known, well tolerated medications that can be used to manage mast cell disease. First line medications include antihistamines, leukotriene inhibitors, and mast cell stabilizers (Cardet 2013, Picard 2013, Molderings 2011, Afrin 2013).

Histamine is released by activated mast cells in large quantities. Histamine acts on the body by interacting with four different types of receptors, called H1, H2, H3 and H4. Medications that block the H1 and H2 receptors are available in plentiful supply in many countries. Once diagnosed, mast cell patients generally begin daily treatment with both H1 and H2 antihistamines. Longer acting, non-sedating H1 blockers like cetirizine are typically used to provide a baseline H1 coverage. H2 coverage is achieved with medications like Zantac or Pepcid. Dosage can be increased as needed to provide effective symptom relief, and these medications are often taken in moderate to high doses by mast cell patients. It is not uncommon to take multiple drugs together to block one type of histamine receptor, but this should be managed by a provider.

Leukotrienes are also released by activated mast cells. Singulair is an example of a leukotriene inhibitor that is a common add-on for mast cell patients. This medication is not a replacement for antihistamines.

Mast cell stabilizers achieve effects by making mast cells less likely to release chemicals. Cromolyn is typically the first line mast cell stabilizer in the US. This medication can take several weeks to demonstrate its full effect, so patients and providers should be aware of this fact. Another mast cell stabilizer, ketotifen, is also available in the US through compounding pharmacies. Ketotifen is also an H1 antihistamine.

Medications should ideally be added one at a time to allow easy identification of a bad actor in the event of a med reaction. As a result, tweaking a patient’s medication regimen takes time and patience. If a patient reacts to a medication, care should be taken to determine if the medication is truly the issue or if it is an inactive ingredient in the preparation (lactose, etc).

Mast cell disease can result in a highly variable clinical picture and mast cell patients are often only diagnosed following years of investigation for other possible causes of their symptoms. For this reason, many mast cell patients have acquired a long list of diagnoses prior to a mast cell diagnosis. In some cases, these diagnoses may be accurate and co-existing. All existing prior diagnoses should be considered for their accuracy in light of a mast cell diagnosis.

Additionally, there are a number of conditions which are frequently comorbid with mast cell disease, including Ehlers Danlos syndrome, postural orthostatic tachycardia syndrome (POTS), a variety of autoimmune diseases and several digestive conditions.  Patients should be evaluated according to their clinical picture and laboratory findings.



Afrin, Lawrence B. Presentation, Diagnosis and Management of Mast Cell Activation Syndrome. 2013. Mast Cells.

Juan-Carlos Cardet, Maria C. Castells, and Matthew J. Hamilton. Immunology and Clinical Manifestations of Non-Clonal Mast Cell Activation Syndrome. Curr Allergy Asthma Rep. Feb 2013; 13(1): 10–18.

Matthieu Picard, Pedro Giavina-Bianchi, Veronica Mezzano, Mariana Castells. Expanding Spectrum of Mast Cell Activation Disorders: Monoclonal and Idiopathic Mast Cell Activation Syndromes. Clinical Therapeutics, Volume 35, Issue 5, May 2013, Pages 548–562.

Gerhard J Molderings, Stefan Brettner, Jürgen Homann, Lawrence B Afrin. Mast cell activation disease: a concise practical guide for diagnostic workup and therapeutic options. Journal of Hematology & Oncology 2011, 4:10.

Not a sad story

About a month ago, I had finally had enough of the oppressive snow wasteland known as Boston and I booked a trip to Florida. I told my masto friend I was coming down and we chirped excitedly about plans and what to do and all of those vacation things. It is no secret that my life has been generally frustrating recently so it seemed like this would provide an appropriate escape.

We made tentative plans for everything in the way only two people with mast cell disease can and generally derped out with excitement. We went back and forth about meds and supplies and safe foods. We decided to go to Disney.

Disney is one of my favorite places and a place I haven’t really had time to explore in several years. It also has an excellent reputation for accommodating health issues (including the very complex ones) and food allergies. We figured we would spend a couple days there, but I didn’t have high expectations for how much I would be able to do. Warm weather is a welcome change given the winter Boston just survived, but I don’t do well in heat, humidity or sunlight, especially when there is a lot of physical stress (like walking or standing for long periods of time). So I pretty much just hoped for the best in the same way I always do. A bad day at Disney is better than a bad day anywhere else.

I flew out of Boston on Thursday. It went pretty smoothly, with the exception of one woman who saw me get out of the wheelchair to walk into the bathroom. When I walked to the sink to wash my hands, she said, “You should be ashamed of yourself, there are people who really need those.” My reply was blistering and ended with, “People like you are the reason people like me kill themselves.” She was stunned to say the least.

Aside from this 90 seconds of unpleasantness, everything else was great. I touched down in Orlando around 6:15 on Thursday night. My friend Nikki picked me up and we checked into our room at the Port Orleans – French Quarter at Disney. It was so pretty. I know all Disney properties are pretty, but I liked this one a lot. We went out to a really nice, allergy safe dinner at a nearby hotel.

The next morning, we medded up and headed for Epcot. I LOVE Epcot. The only thing I wanted to do there was go to all the countries in the World Showcase. We got some (allergy safe) food and made it to all the countries before it started pouring. We covered our (accessed) ports and ran for the bus back to hotel.

It was a little hairy with gummy dressings and symptoms from the sudden temperature change, but we took meds and handled it. We took a nap back at the hotel and headed over to Magic Kingdom around 8. We went on the Haunted Mansion, It’s a Small World, Space Mountain and the new Seven Dwarfs Mine Ride, saw the fireworks and caught the end of the Electric Light Parade. We got back to the room around midnight and crashed hard, but in that exhausted way where you can’t sleep.

We had originally only booked two nights at Disney because we are crazy people who overestimated our physical capabilities. I figured that if we wanted to extend, it would be possible, even if we needed to switch hotels. I didn’t realize it was the start of Florida school vacation. We had called the Disney reservation line several times on Friday and they kept telling us nothing was available. Around 3am, I figured I would search online for available rooms since I wasn’t sleeping anyway and there was a room available at French Quarter! So I booked it and then we could not have to worry about waking up early to pack and also lack of sleep is one of my worst triggers so I had been worried about that. We got really lucky and slept in before heading to Animal Kingdom in the afternoon.

I have never seen a lot of the things at Animal Kingdom before so I was really excited. We went on the safari and saw lots of savannah animals, like giraffes, lions, zebras and hippos. We had booked fast passes for some rides so we did a lot of running around. (I should probably mention here that running is not something I do or tolerate well.) We went on this Mt. Everest roller coaster which was SO MUCH FUN (side note: at this point I learned that if you have a port and are on a roller coaster going backwards, it will feel like your port is pushing through your chest wall. It was really funny, when we started going backwards, both Nikki and I put our hands on our ports at the same time). We went back to the hotel and napped for a while and then took the ferry to Downtown Disney to get some food and watch Insurgent.

I was thoroughly fried by this point, and in that super uncomfortable, muscles hurt, about to react/actually reacting, nausea/vomiting space that I really hate. I was nauseous pretty much the whole time, but it was getting worse. I slept really late the next day and met Nikki at the MGM park, which I had also never seen in its entirety. We saw the Indiana Jones show, the Great Movie ride, a really cool stunt driving show and the Star Wars ride. At this point I was feeling the liquid courage effect of Benadryl so we waited in line (in the shade) for an hour for the Aerosmith Rockin’ Roller Coaster (which is one of my all time favorite roller coasters). It did not disappoint. Then there was only a short line for the Tower of Terror so we did that, too.

So, to summarize: two mast cell patients (who have had multiple surgeries, require regular IV meds and semi-regular epi, and have complicated food restrictions) went to Disney for three days, saw all four parks and Downtown Disney, ate food they didn’t prepare themselves and through the use of naps and liberal application of medication/IV fluids, were able to see/do literally all of the things they wanted to. LIKE FUCKING BOSSES.

Now we are at Nikki’s farm outside of Ocala which is very farmy and very beautiful. It is so calm here (except when the dogs and the pigs fight because the baby pig wants them to play with her, but still). I am recovering from the visceral adventures of Disney and feeling very glad that I came.

I try very hard to depict my life as realistically as possible, the good and the bad. I am in a place in my life right now where my life is hard a lot of the time and so that is what I write about. It’s not always my reality, it’s just my reality right now.

Everyone has hard things in their lives. I don’t think that being sick is any harder than losing a parent or a difficult divorce. It’s just different, and because my particular illness is unusual and uncommon, it seems worse to people. People say things to me sometimes, about how sad it makes them that I’m so young and so sick, or that I need a colostomy, or that I have a port, or whatever. They think my life is sad or tragic. My life is neither of those things.

I think sometimes that it’s easy to get stuck on how hard things are and how upsetting it is that you will never have your old life again. But we have these bright spots, and you can choose to elevate them in your mind so that they wash out the hard things, at least for a little while.

Don’t pity me, or people like me. This is my life, and it’s not a sad story.



Allergic effector unit: The interactions between mast cells and eosinophils

Eosinophils are granulocytes that can localize to the tissues under certain conditions, including allergic response. Eosinophilic granules contain the positively charged proteins major basic protein, eosinophil peroxidase, eosinophil cationic protein, and eosinophil-derived neurotoxin. Like mast cells, eosinophils release these granules in response to many things, including inflammatory signals, parasitic infection, tissue damage and allergic inflammation. They express many receptors, including receptors for platelet activating factor (PAF) and histamine receptors. PAF and histamine are both released by mast cells.

Mast cells and eosinophils are overwhelmingly found together in late and chronic stages of allergic inflammation. They function in such close concert that mast cells, eosinophils and their effects have been termed the allergic effector unit (AEU). Mast cells release signals that affect eosinophil behavior and receive signals from eosinophils. These cells often also function while in physical contact with one another. When eosinophils are in physical contact with mast cells, they live longer than normal. CD48, 2B4, DNAM-1 and Nectin-2 are all involved in the mast cell – eosinophil contact mechanism.

Major basic protein can activate mast cells and eosinophil peroxidase is taken up by mast cells as a signaling molecule. Tryptase draws eosinophils to mast cells and causes release of eosinophil peroxidase, IL-6 and IL-18 from eosinophils. Histamine and prostaglandin D2 also signal eosinophils to migrate towards mast cells. Mast cell secreted eotaxin activates eosinophils by the histamine 4 (H4) receptor. Both cell types secrete leukotrienes and both express leukotriene receptors.

When grown together, researchers are able to investigate the behavior of mast cells and eosinophils together. This is called co-culture. In 29% of cases, eosinophils will migrate towards resting (non-activated) mast cells. In 45% of cases, eosinophils will migrate towards IgE activated mast cells. In 47% of cases, eosinophils will migrate towards mast cells activated through a non-IgE pathway. The specific attractant signal has not been identified.

When co-cultured with eosinophils, basal mast cell mediator release was 5% higher. When the mast cells were activated by IgE, degranulation was 15% higher. In order to activate mast cells, eosinophils must be in contact with them. However, mast cells can activate eosinophils without contact. In co-cultures with mast cells, eosinophil peroxidase constituted 47% of eosinophil released proteins, compared with 18% normally.

In low term co-cultures, both mast cells and eosinophils stayed activated. TNF was high in the co-culture, but not IL-6, IL-8 and IL-10. Importantly, low relative numbers of mast cells could activate eosinophils, but mast cell activation was most effective when eosinophils were more numerous. Eosinophils are thought to reduce the threshold of mast cell responsiveness to IgE.



Elishmereni M, Bachelet I, Nissim Ben Efraim AH, Mankuta D, Levi-Schaffer F. Interacting mast cells and eosinophils acquire an enhanced activation state in vitro. Allergy 2013; 68: 171–179.

Elishmereni M, Alenius HT, Bradding P, Mizrahi S, Shikotra A, Minai-Fleminger Y, et al. Physical interactions between mast cells and eosinophils: a novel mechanism enhancing eosinophil survival in vitro. Allergy 2011;66:376–385.

Minai-Fleminger Y, Elishmereni M, Vita F, Soranzo MR, Mankuta D, Zabucchi G et al. Ultrastructural evidence for human mast cell-eosinophil interactions in vitro. Cell Tissue Res 2010;341:405–415.

Puxeddu I, Ribatti D, Crivellato E, Levi- Schaffer F. Mast cells and eosinophils: a novel link between inflammation and angiogenesis in allergic diseases. J Allergy Clin Immunol 2005;116:531–536.