Increased production of leukotrienes can be demonstrated
in asthmatic patients. Measurement of LTE4
excretion in urine is a convenient method for examining
leukotriene production in vivo. Thus, increased urinary
leukotrienes have been demonstrated following
allergen challenge, during acute asthma, and aspirininduced
asthma [36–41]. However, no increase in LTE4
excretion was shown after exercise-induced asthma [42],
despite the fact that leukotriene antagonists inhibit this
response [43]. Raised levels of leukotrienes, particularly
LTE4 have been found in bronchoalveolar lavage fluid
of asthmatic volunteers [44–46], with further increases
after endobronchial allergen challenge [47].