Category: immune_innate
Mast cells release preformed (histamine, tryptase, heparin) + newly synthesized (LTC4, LTD4, LTE4, PGD2, TNF-α) mediators on IgE-FcεRI crosslinking. Cromolyn + nedocromil stabilize mast cells (mechanism debated — possibly Ca²⁺ channel modulation). Leukotrienes (5-LOX pathway from arachidonic acid — cross-link: arachidonic_acid_cascade): LTB4 = chemoattractant; LTC4/D4/E4 (cysteinyl-LTs) = bronchoconstriction + vascular permeability + mucus + airway remodeling. Therapeutic blockade: 5-LOX inhibitor zileuton (blocks LT synthesis); cysteinyl-LT1 receptor antagonists montelukast + zafirlukast (asthma + allergic rhinitis). PDE4-i (roflumilast, apremilast) reduce inflammatory mediator release via cAMP elevation.