Airway responsiveness to leukotriene C4 (LTC4), leukotriene E4 (LTE4) and histamine in aspirin-sensitive asthmatic subjects.

ABSTRACT

We wanted to determine whether the airway response to inhaled leukotriene C4 (LTC4) is similar to inhaled leukotriene E4 (LTE4) in aspirin-sensitive asthma and, therefore, determined airway responsiveness to histamine, LTC4 and LTE4 in seven aspirin-sensitive subjects and 13 control asthmatic subjects, who were tolerant of aspirin. The concentration of inhaled lysine-aspirin which produced a 15% fall in forced expiratory volume in one second (FEV1) (PC15) was determined in aspirin-sensitive asthmatic subjects. The dose of histamine, LTC4 and LTE4 which produced a 35% fall in specific airways conductance (PD35sGaw) was determined by linear interpolation from the log dose response curve. There was no correlation between the PC15 for lysine-aspirin and the airway reactivity to inhaled LTC4 or LTE4. There was no difference in airway response to histamine and LTC4 between any of the groups of asthmatic subjects. There was a rank order of potency LTC4 > LTE4 > histamine in both groups, with LTC4 approximately 1,000 fold more potent than histamine in both groups. Aspirin-sensitive asthmatic subjects were significantly more responsive to LTE4 (p = 0.02) than aspirin-tolerant asthmatic subjects. The relative responsiveness of LTE4 to histamine (PD35 histamine/PD35 LTE4) was significantly greater in aspirin-sensitive asthmatic subjects compared to aspirin-tolerant asthmatic subjects (p = 0.05). There was no difference in relative responsiveness of LTC4 to histamine between aspirin-sensitive or aspirin-tolerant asthmatic subjects. We conclude that the airways of aspirin-sensitive asthmatic subjects demonstrate a selective hyperresponsiveness to LTE4, which is not observed for LTC4.