Background: Cysteinyl leukotrienes (LTs) and thromboxane A2 (TXA2) are known to play an essential role in the pathogenesis of atopic asthma. However, their role in nonatopic asthma has not as yet been clarified. The objectives of this study were to define (1) the participation of LTs and TXA2 in nonatopic asthma and (2) the relationship between LTs and TXA2 in asthma attacks.
Methods: Urinary excretion of leukotriene E4 (LTE4) and 11-dehydrothromboxane B2 (11DTXB2) was measured in 10 atopic and 10 nonatopic asthmatics who were admitted to hospital with either an acute asthma attack or status asthmaticus.
Results: In atopic asthmatics, urinary excretion of LTE4 and 11DTXB2 was significantly higher on admission with an asthma attack, and returned to control levels when the patients were in the improved state (179+/-29 to 65+/-16 ng/day in LTE4, 1,085+/-250 to 440+/-90 ng/day in 11DTXB2). Similar findings were observed in nonatopic asthmatics (148+/-13 to 61+/-11 ng/day in LTE4, 1,089+/-206 to 457+/-60 ng/day in 11DTXB2). However, when the individual data during the attack were analyzed, there was no correlation between urinary excretion of LTE4 and that of 11DTXB2 in both types of asthma.
Conclusion: Both LTs and TXA2 may be implicated in the pathogenesis of the nonatopic as well as the atopic type of asthma, but no correlation between these two metabolites was observed in the individuals.