Every person has a collection of mast cells. These are considered “allergy cells” and activate when an allergen enters the body, beginning an immediate allergic reaction. When mast cells become activated in response to an allergen, they release mediators – products either stored within the cell or produced by the cell. When mediators are released into the body, allergy symptoms develop.
While allergens are the first and foremost reason for the activation of mast cells, other things, such as medications, infections, or insect bites, can also affect the cell’s response. This type of reaction is known as secondary activation. In some cases, mast cells can release mediators in response to things that do not pose an allergy threat or are considered abnormal. This activation occurs when mast cells become defective and do not function properly.
When a mutation occurs within mast cells, clones are produced and go on to release the mediators even when they are not needed. When a person has repeated episodes of allergy symptoms because of defective mast cells, it is known as mast cell activation syndrome (MCAS).
What are MCAS symptoms?
The symptoms that develop in people with MCAS are consistent with anaphylaxis or an allergic reaction. The symptoms can affect the lungs, gastrointestinal tract, skin, and heart. There are various types of symptoms that can occur in MCAS, such as:
- Tachycardia (rapid pulse or heartbeat)
- Hypotension (low blood pressure)
- Syncope (fainting)
- Skin flushing or turning red
- Shortness of breath
- Hearing a harsh noise when breathing
- Difficulty breathing
- Throat swelling
- Swelling of the tongue or lips
- Abdominal pain
- Eye irritation, itching, or watery eyes
- Itchy and runny nose
A person with MCAS may not experience every symptom listed above. It depends on how the body reacts to the increased and unnecessary activation of mast cells.
In more severe cases of MCAS, a person can go into anaphylactic shock. When that happens, symptoms include:
- A rapid and dangerous drop in blood pressure
- A weakened pulse
- Feeling lightheaded
- Quick and shallow breathing
- Loss of consciousness
Anaphylactic shock is a medical emergency and requires immediate medical care.
What causes MCAS disease?
Although medical researchers are unsure what causes MCAS, they have a few ideas based on the type. One such theory is that genetics play a role. However, more research is needed to confirm that genetics are wholly to blame.
There are three types of MCAS. They include:
- Primary MCAS: A mutation known as KIT D816V is thought to contribute to primary MCAS. The mast cells in this type of mutation display CD25. In primary MCAS, mastocytosis is confirmed, meaning the body produces more mast cells than it needs.
- Secondary MCAS: In secondary MCAS, it’s thought that the immune system may play a role, specifically in immunologic conditions. Specific antibodies known as IgE contribute to the reaction in secondary MCAS.
- Idiopathic MCAS: When a person has this type of MCAS, there is no known cause. Both the mutations and creation of too many mast cells found in primary MCAS and the immune component in secondary MCAS are not a part of this form of the disease.
Typically, only secondary MCAS has possible triggers. Primary and idiopathic MCAS can cause symptoms unrelated to exposure to allergens or any other stimuli.
What is the best treatment for mast cell activation syndrome?
There is no known cure for MCAS. However, there are several treatments available that can manage the syndrome and control symptoms. Some treatment options include:
- H1 or H2 antihistamines: Antihistamines block the symptoms of an allergic reaction by blocking the effects of histamines. Histamines are one of the primary mediators released by mast cells in response to an allergen. When a person takes antihistamines, they hinder the action of the histamines released by mast cells and prevent symptoms.
- Aspirin: In people who experience skin flushing and redness, aspirin may help to control or decrease these symptoms.
- Mast cell stabilizers: There are certain medications designed to prevent mast cells from being able to release mediators. They can decrease the number of anaphylactic episodes a person has with MCAS.
- Antileukotrienes: Leukotrienes are another type of mediator released from mast cells that contribute to the symptoms of MCAS. Taking this type of medication will block the action of this particular mediator in an attempt to reduce symptoms.
- EpiPen: For people who experience severe anaphylactic shock, carrying an EpiPen is necessary. In the event of a reaction, they can inject themselves to help curb symptoms before they arrive at the hospital.
While MCAS can interfere with a person’s daily life, the treatment options mentioned above can manage the syndrome so that the symptoms are more controlled. MCAS isn’t always easy to deal with, but until a cure is found, management can allow people with this syndrome to live a normal life.
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