RT Journal Article
SR Electronic
T1 Reduced late asthmatic response by repeated low-dose allergen exposure
JF European Respiratory Journal
JO Eur Respir J
FD European Respiratory Society
SP 872
OP 880
DO 10.1183/09031936.01.17508720
VO 17
IS 5
A1 M. Palmqvist
A1 Z-H. Cui
A1 M. Sjöstrand
A1 A. Lindén
A1 J. Lötvall
YR 2001
UL http://erj.ersjournals.com/content/17/5/872.abstract
AB Allergic asthmatic individuals are often exposed to low-doses of allergen in their everyday life. Extended exposure to allergen has lead to down-regulation of the allergic process in cell systems and in animal models. The aim of this study was to evaluate whether any such inhibitory mechanism of allergic responses can be seen in man in vivo.Patients with mild asthma were repeatedly and double-blindly exposed to 25% of the individual dose of allergen that caused an early (EAR) and late asthmatic reaction (LAR). One day after the low-dose allergen or placebo exposure periods, the same individual was given a high-dose allergen challenge. Sputum and blood were collected for the evaluation of eosinophils.Exposure to repeated low doses of allergen induced increased bronchial methacholine responsiveness 6 h after the final allergen exposure (p=0.018), and an increase in the number of eosinophils in sputum. By contrast, the late asthmatic response after challenge with a high dose of allergen was significantly attenuated by ∼30% at 24 h after the final low-dose allergen exposure (p=0.03).In summary, repeated low doses of allergen given directly to the airways, attenuate the high-dose allergen-induced late response, despite enhanced bronchial hyperresponsiveness to methacholine and elevated sputum eosinophils prior to allergen challenge.This work was supported financially bythe Vårdal Foundation and the Swedish Heart and Lung Foundation. M. Palmqvist and J. Lötvall were financed by Herman Krefting's Foundation against Asthma-Allergy.