M-E Boulay1, L-P Boulet. 1. Centre de recherche de l'Hôpital Laval, Institut universitaire de cardiologie et de pneumologie de l'Université Laval, Sainte-Foy, Québec, Canada.
Abstract
BACKGROUND: Low-dose allergen challenge (LDAC) may be a useful tool for studying the capacity of allergens to induce airway inflammation in atopic subjects. OBJECTIVE: To evaluate lower airway inflammatory changes following repeated inhalation of very low doses of allergen (VLDAC) in non-asthmatic subjects with allergic rhinitis (NAAR) compared with mild allergic asthmatic subjects (AA). METHODS: Fourteen NAAR and 11 AA were seen out of the pollen season and had skin prick tests with common aeroallergens. Baseline spirometry (S) and methacholine challenge (MC) were done and blood and induced sputum (IS) differential cell counts were obtained. Each subject underwent VLDAC on four consecutive mornings with a relevant allergen. S, MC, and blood and IS samplings were repeated 6 h after the second and fourth VLDAC and one week later. RESULTS: Although there were, as expected, no changes in FEV1 or PC20 in either group, mean percentage eosinophils on IS were significantly increased in NAAR on day 2 of VLDAC and decreased in all but one subject on day 4, with a tendency to return to baseline levels one week later. In AA, there was a non-significant trend for sputum eosinophils to increase on day 2; four subjects showed a decrease of eosinophils on day 4 of VLDAC. There was a correlation between eosinophil cationic protein (ECP) levels and eosinophil counts in NAAR throughout the study. There were no variations in other sputum cells or blood inflammatory cells. CONCLUSION: VLDAC can increase the percentage of eosinophils in IS of NAAR subjects without associated respiratory symptoms nor physiological modifications. A reduction in eosinophilic response despite repeated exposure, more common in NAAR subjects, suggests an adaptation process that needs to be further evaluated.
BACKGROUND: Low-dose allergen challenge (LDAC) may be a useful tool for studying the capacity of allergens to induce airway inflammation in atopic subjects. OBJECTIVE: To evaluate lower airway inflammatory changes following repeated inhalation of very low doses of allergen (VLDAC) in non-asthmatic subjects with allergic rhinitis (NAAR) compared with mild allergic asthmatic subjects (AA). METHODS: Fourteen NAAR and 11 AA were seen out of the pollen season and had skin prick tests with common aeroallergens. Baseline spirometry (S) and methacholine challenge (MC) were done and blood and induced sputum (IS) differential cell counts were obtained. Each subject underwent VLDAC on four consecutive mornings with a relevant allergen. S, MC, and blood and IS samplings were repeated 6 h after the second and fourth VLDAC and one week later. RESULTS: Although there were, as expected, no changes in FEV1 or PC20 in either group, mean percentage eosinophils on IS were significantly increased in NAAR on day 2 of VLDAC and decreased in all but one subject on day 4, with a tendency to return to baseline levels one week later. In AA, there was a non-significant trend for sputum eosinophils to increase on day 2; four subjects showed a decrease of eosinophils on day 4 of VLDAC. There was a correlation between eosinophil cationic protein (ECP) levels and eosinophil counts in NAAR throughout the study. There were no variations in other sputum cells or blood inflammatory cells. CONCLUSION: VLDAC can increase the percentage of eosinophils in IS of NAAR subjects without associated respiratory symptoms nor physiological modifications. A reduction in eosinophilic response despite repeated exposure, more common in NAAR subjects, suggests an adaptation process that needs to be further evaluated.
Authors: Gail M Gauvreau; Beth E Davis; Guy Scadding; Louis-Philippe Boulet; Leif Bjermer; Adam Chaker; Donald W Cockcroft; Barbro Dahlén; Wyste Fokkens; Peter Hellings; Nikolaos Lazarinis; Paul M O'Byrne; Ellen Tufvesson; Santiago Quirce; Maurits Van Maaren; Frans H de Jongh; Zuzana Diamant Journal: Eur Respir J Date: 2022-08-25 Impact factor: 33.795
Authors: Stephane Esnault; Elizabeth A Kelly; Elizabeth A Schwantes; Lin Ying Liu; Larissa P DeLain; Jami A Hauer; Yury A Bochkov; Loren C Denlinger; James S Malter; Sameer K Mathur; Nizar N Jarjour Journal: PLoS One Date: 2013-07-02 Impact factor: 3.240
Authors: Vanessa J Kelly; Tilo Winkler; Jose G Venegas; Mamary Kone; Daniel L Hamilos; Roshi Afshar; Josalyn L Cho; Andrew D Luster; Benjamin D Medoff; R Scott Harris Journal: PLoS One Date: 2015-12-07 Impact factor: 3.240