UNDERSTANDING MAST CELLS AND MAST CELL MEDIATED DISORDERS

Mast cells (MCs) are versatile components of the immune system, traditionally recognized for their roles in IgE-mediated allergic responses such as anaphylaxis and asthma. However, recent evidence highlights their broader involvement in innate and adaptive immunity, tissue remodeling, neuroim-mune regulation, and various inflammatory diseases. This chapter provides an in-depth overview of the biology and function of MCs, beginning with their historical discovery, structural features, and differentiation pathways from hematopoietic stem cells. The molecular mechanisms of MC activation are explained, including both immunoglobulin E (IgE)-dependent pathways via FcRI and non-IgE triggers such as MRGPRX2, neuropeptides, and environmental stimuli. The chapter further elaborates on the diverse range of mediators released by MCs; preformed granule-associated components like his-tamine and tryptase, newly synthesized lipid mediators including prostaglandins and leukotrienes, as well as cytokines and extracellular vesicles. These mediators contribute to the pathogenesis of various clinical conditions, including mastocytosis, chronic urticaria, allergic rhinitis, atopic dermatitis, and exercise-induced anaphylaxis. Moreover, their role in sensory modulation, such as pain and pruritus, is discussed. The diagnostic and therapeutic implications of MC activation, including the use of trypt-ase as a biomarker and current pharmacologic strategies targeting MC pathways are also discussed. Overall, the chapter provides a comprehensive and updated understanding of MCs and their relevance in health and disease.