RT Journal Article SR Electronic T1 Methacholine and adenosine 5′-monophosphate challenges in children with post-infectious bronchiolitis obliterans JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 36 OP 41 DO 10.1183/09031936.06.00019605 VO 27 IS 1 A1 Yoo, Y. A1 Yu, J. A1 Kim, D. K. A1 Choi, S. H. A1 Kim, C. K. A1 Koh, Y. Y. YR 2006 UL http://erj.ersjournals.com/content/27/1/36.abstract AB Airway hyperresponsiveness (AHR) is a characteristic feature of asthma, but is also frequently demonstrated by children and adults with chronic obstructive lung diseases. AHR is usually measured by bronchial challenges using direct or indirect stimuli. The aim of this study was to compare these two types of bronchial challenge in children with post-infectious bronchiolitis obliterans (BO). Methacholine and adenosine 5′-monophosphate (AMP) challenges were used as tools for the evaluation of AHR to direct and indirect stimuli, respectively, in children with post-infectious BO (n = 28). These results were compared with those of asthmatic (n = 30) and control children (n = 25). Altogether, twenty-two patients (78.6%) with post-infectious BO were hyperreactive to methacholine with a provocative concentration causing a 20% fall in forced expiratory volume in one second (PC20) of <16 mg·mL−1, but only six (21.4%) were hyperreactive to AMP with a PC20 of <200 mg·mL−1. All patients with asthma responded positively to methacholine, and most (28, 93.3%) also responded positively to AMP. The majority of controls were insensitive to both challenges. Airway hyperresponsiveness to methacholine is a frequent, but by no means universal, finding in children with post-infectious bronchiolitis obliterans, but is usually not accompanied by airway hyperresponsiveness to adenosine 5′-monophosphate. This finding suggests that airway hyperresponsiveness in patients with post-infectious bronchiolitis obliterans has characteristics that differ from those of asthmatic subjects.