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. 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. Glutathione Cell Defense Glutathione: Master Antioxidant, Reducing Oxidative Stress, and Detoxification Mast Cell Activation Syndrome (MCAS) Dr. Todd Maderis