LTC4S (leukotriene C4 synthase) is a membrane-bound enzyme that catalyzes the conjugation of leukotriene A4 with glutathione to produce leukotriene C4, a critical inflammatory mediator 1. The enzyme is highly expressed in mast cells, where over 95% of bronchial mast cells express high levels of LTC4S, making them the dominant cellular source rather than eosinophils 1. Beyond classical leukotriene biosynthesis, LTC4S also produces resolution-phase mediators by converting epoxide precursors to specialized proresolving molecules like MCTR1 and RCTR1, which have anti-inflammatory and tissue regeneration properties 23. The enzyme plays a significant role in asthma pathogenesis, with genetic polymorphisms in the LTC4S gene (-444A/C) showing associations with asthma risk in specific populations, particularly Caucasians and aspirin-tolerant individuals 4. In aspirin-exacerbated respiratory disease (AERD), LTC4S overexpression contributes to excessive cysteinyl leukotriene production 5. Clinically, higher densities of LTC4S-positive mast cells correlate with reduced lung function and greater bronchial reversibility in asthma patients 1, making LTC4S both a therapeutic target for anti-inflammatory drugs and a potential biomarker for asthma severity.