Cysteinyl leukotrienes are potent bronchoconstrictors, inducers of
airway microvascular leakage and oedema, and of mucus secretion, in addition to
causing an eosinophilic airway infiltration. Increased urinary excretion of the cysteinyl
leukotriene E4 (LTE4) has been demonstrated following allergen challenge
and during acute asthma attacks.