Mast cell Wikipedia 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. Did you know one single mast cell can release chemicals that affect your skin, gut, heart, brain, and immune system all at once? That's why MCAS can feel so overwhelming, the Frontiers Ironing out COPD: ferroptosis driven immune dysregulation, metabolic rewiring, and precision therapeutic opportunities Mast Cells British Society for Immunology