Many online searches for “mine cells” are the result of a common misspelling of the term “mast cells.” These cells are a type of white blood cell and part of the immune system. Mast cells are produced in the bone marrow and can be found in connective tissues throughout the body, particularly near blood vessels, in the respiratory tract, and under the skin.
These cells are classified as granulocytes because they contain granules, which are small sacs filled with chemicals. When mast cells are activated, they release the contents of these granules into the surrounding tissues, a process known as degranulation.
The Role of Mast Cells in the Immune System
Mast cells act as sentinels for the innate immune system, the body’s non-specific defense mechanism. They are strategically positioned at the boundaries between tissues and the external environment, such as the skin, lungs, and digestive tract. This placement allows them to quickly detect and respond to foreign invaders like bacteria, viruses, and parasites.
When a mast cell recognizes a pathogen, it undergoes degranulation, releasing chemical mediators like histamine and heparin to initiate an inflammatory response. The released mediators increase blood flow to the affected area and make blood vessels more permeable. This allows other immune cells, such as neutrophils, to move from the bloodstream into the tissue to help clear the pathogen. This inflammatory cascade is part of the body’s defense and wound-healing processes.
Mast Cells and Allergic Reactions
While mast cells play a protective role, their activity can be directed against harmless substances, leading to allergic reactions. In individuals with allergies, the immune system mistakenly identifies a substance, like pollen or pet dander, as a threat. This triggers the production of a specific type of antibody called Immunoglobulin E (IgE).
These IgE antibodies travel through the bloodstream and attach to the surface of mast cells. Upon subsequent exposure, the allergen binds directly to the IgE antibodies on the mast cells. This binding event triggers degranulation, causing a release of histamine and other inflammatory mediators into the surrounding tissues.
The flood of mediators is responsible for the symptoms of an allergic reaction. Histamine, for instance, causes blood vessels to dilate and become leaky, leading to swelling and redness. It also stimulates nerve endings, causing itching, and increases mucus production, resulting in a runny nose and watery eyes. In more severe cases, this process can affect the entire body, causing a systemic reaction known as anaphylaxis, or contribute to chronic conditions like asthma.
Mast Cell Activation Disorders
Mast cells can also be the source of chronic health issues. These conditions, known as mast cell activation disorders, are distinct from allergies because the problem lies with the mast cells themselves, which become dysfunctional. They are characterized by the inappropriate and excessive release of cellular mediators, leading to a wide range of symptoms.
One such condition is Mast Cell Activation Syndrome (MCAS), where mast cells are hyper-reactive and degranulate in response to minor or even unidentified triggers. This results in repeated episodes of allergic-like symptoms, often affecting multiple body systems simultaneously, including the skin, gastrointestinal tract, and cardiovascular system. Unlike a standard allergy, the symptoms in MCAS can be chronic and seemingly random.
A different, rarer disorder is mastocytosis, which involves the abnormal accumulation of too many mast cells in various tissues like the skin, bone marrow, or internal organs. The main distinction is that MCAS is a disorder of mast cell over-activation, while mastocytosis is a disorder of over-production. The presence of an abnormally high number of mast cells in mastocytosis means that even normal activation can lead to a release of mediators and severe symptoms.
Regulating Mast Cell Activity
Managing the activity of mast cells is the goal for treating conditions like allergies and mast cell disorders. Therapeutic approaches fall into two categories: medications that counteract the effects of mast cell mediators and those that prevent the cells from releasing them.
Antihistamines are a common treatment that works by blocking the action of histamine after it has been released from mast cells. There are different types, such as H1 blockers that help with symptoms like itching and flushing, and H2 blockers that can address gastrointestinal issues. These medications do not stop the degranulation process itself but rather mitigate its downstream effects.
Another class of drugs, known as mast cell stabilizers, works differently. Medications like cromolyn sodium help to prevent mast cells from degranulating when triggered. By stabilizing the cell membrane, these drugs inhibit the release of histamine and other mediators. For individuals with chronic mast cell issues, lifestyle approaches, such as identifying and avoiding personal triggers for degranulation, can also be an important part of a management plan.