Mast Cell Activation Syndrome: A Primer for the Gastroenterologist Digestive Diseases and Sciences Springer Nature Link Invisible Pain Series: Mast Cell Activation Syndrome POGO Physio Gold Coast Mast cells are hypersensitive immune cells that release histamine and other inflammatory mediatorsoften in response to oxidative stress, environmental toxins, and immune imbalance. Many patients with MCAS have low levels of glutathione. Calming the Chaos: How Ozone and Light Therapy Help with Mast Cell Activation Syndrome (MCAS) in Oklahoma City Venturis Clinic