Mast cells: A dark horse in osteoarthritis treatment 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. Diagnostic criteria of mast cell activation syndrome Download Scientific Diagram Mast Cell Activation Syndrome: The Hidden Culprit Behind Mysterious Multi System Symptoms Dr. Jill Carnahan, MD