05/27/2026
Mast cells are specialized white blood cells that act as frontline defenders in the immune system by storing and releasing histamine, a powerful chemical involved in inflammation and allergic reactions. When mast cells detect threats such as allergens, parasites, or infections, they undergo a process called degranulation, releasing histamine into nearby tissues.
Histamine then binds to receptors throughout the body, causing blood vessels to widen, increasing swelling and redness, stimulating nerves that trigger itching, tightening airway muscles that may lead to coughing or wheezing, and activating the digestive tract, sometimes resulting in cramps or diarrhea. While this response helps protect the body, excessive histamine release can contribute to allergies and conditions such as mast cell activation synd