AAAAI Mast Cell Disorders Committee Work Group Report: Mast cell activation syndrome (MCAS) diagnosis and management Journal of Allergy and Clinical Immunology Managing Mast Cell Activation Syndrome (MCAS) Stabilizers Mast Cell Activation Syndrome (MCAS) Dr. Todd Maderis Mast cell stabilisers, leukotriene antagonists and antihistamines: A rapid review of the evidence for their use in COVID 19 The Centre for Evidence Based Medicine 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.