Symptoms of atopic
asthma often decrease or even seem to disappear around puberty. The aim of this study was to investigate whether this so-called clinical remission is accompanied by remission of airway
inflammation, since symptoms relapse in a substantial proportion of subjects later in life. To assess indicators of
inflammation and/or structural damage of the airways, exhaled
nitric oxide (eNO) and bronchial responsiveness to adenosine-5'-monophosphate (
AMP) and
methacholine (MCh) were determined in 21 subjects in clinical remission of atopic
asthma. Clinical remission was defined as complete absence of symptoms of
asthma without the use of any medication in the year preceding the study. Results were compared with those of 21 patients with current
asthma and 18 healthy control subjects. We found significantly higher eNO values in the remission group than in healthy controls (geometric mean, 18.9 and 1.0 ppb, respectively; p < 0.001) whereas eNO values of the remission group and those of the subjects with current
asthma (geometric mean, 21.9 ppb) were similar (p = 0.09). The responsiveness to both
AMP and MCh of subjects in clinical remission was significantly higher as compared with responsiveness of healthy controls, and lower than responsiveness of subjects with current
asthma. A significant correlation could be established between eNO and responsiveness to
AMP, but not between eNO and responsiveness to MCh. The results of this study are suggestive of persistent airway
inflammation during clinical remission of atopic
asthma. We speculate that subclinical
inflammation is a risk factor for
asthma relapse later in life, and that eNO and responsiveness to both
AMP and MCh can be used as different, noninvasive indices of the inflammatory process of the airways.