Mast Cell Activation (MCAS)

Mast cells are immune cells that are involved in allergic reactions such as hives, anaphylaxis, dermatographia, and sometimes intestinal inflammation. Mast cells can become activated by two things: allergens or autonomic nerves. Mast Cell Activation Syndrome (MCAS) is a condition defined by abnormal mast cell activation and allergic reactions - but without any obvious allergic cause. (For allergic reactions with a known cause, see the "Immunology, Inflammation, Allergies" forum.)