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 in autoimmune disease Nature Mast Cell Activation Syndrome (MCAS): A Functional Approach to Histamine Intolerance Accurate Education Mast Cell Activation Disease (MCAD) Accurate Clinic