Serum ECP and MPO, but not urinary LTE4, are associated with bronchial hyper-responsiveness

A random population-based sample of 131 subjects was used to assess the val ue of serum eosinophil cationic protein (ECP), serum myeloperioxidase (MPO) , and urinary leukotriene E-4 (LTE4) in predicting branchial hyperresponsiv eness measured by methacholine challenge. Special interest was focused on t he history of aspirin intolerance and on smoking as contributing factors. The mean serum ECP and MPO were higher in hyper-reactive [provocational dos e causing a 20% fall in forced expiratory volume in 1 sec. (PD20) less than or equal to 6900 mu g] than in non-hyper-reactive subjects (22.3 vs. 13.2 mu g l(-1), P < 0.001 and 377 vs. 278 mu g l(-1), P = 0.001, respectively). This was also seen in current smokers vs. never smokers (17.2 vs. 12.9 mu g l(-1), P = 0.03 and 372 vs. 286 mu g l(-1), P = 0.04, respectively). Ther e were no differences in baseline urinary excretion of LTE4 between hyper-r eactive and non-hyper-reactive subjects. During the 2 h after methacholine challenge, urinary LTE4 excretion increased from 53.8 and 69.0 ng mmol(-1) creatinine in non-hyper-reactive subjects, but there was no change in hyper -reactive subjects (non-hyper-reactive vs. hyper-reactive, P = 0.06). The i ncrease was greatest in subjects with aspirin intolerance causing urticaria or angioedema but not aggravation of asthma (from 58.5 to 87.2 ng mmol(-1) creatinine), probably due to extrapulmonary leukotriene production. Our results indicate that serum ECP and MPO, but not urinary LTE4 (even in subjects with a history of aspirin intolerance), predict branchial hyper-re sponsiveness to methacholine. The subject's smoking history must be taken i nto account when these parameters are considered. (C) 1999 Harcourt Publish ers Ltd.