Published ahead of print on June 3, 2005, doi:10.1164/rccm.200502-272OC
© 2005 American Thoracic Society doi: 10.1164/rccm.200502-272OC
Repeated Exposure to Ozone Increases Alveolar Macrophage Recruitment into Asthmatic AirwaysLung Biology Center, Department of Medicine, University of California, San Francisco; and Division of Environmental Health Sciences, School of Public Health, University of California, Berkeley, California Correspondence and requests for reprints should be addressed to John R. Balmes, M.D., University of California–San Francisco, Box 0843, San Francisco, CA 94143-0843. E-mail: jbalmes{at}itsa.ucsf.edu Rationale: Repeated, short-term exposures to ozone (O3) lead to attenuation of the acute lung function and airway inflammatory responses seen after a single exposure in healthy subjects, but it is unclear whether these acute responses also attenuate in subjects with asthma. Objective: To address this question by exposing 14 subjects with asthma to 0.2 ppm O3 for either 4 hours on a single day or 4 hours on 4 consecutive days (multiday [MD]). At least 3 weeks later, subjects underwent the alternate exposure. Methods: Spirometry was performed immediately pre- and postexposure and bronchoalveolar lavage (BAL) was obtained 18 hours after each exposure. Main Results: The decrease in FEV1 was greatest across Day 2 of the MD (MD2) exposure and then gradually declined on successive days of the MD exposure (mean ± SD decrease in FEV1 of 25.4 ± 18.0% across MD2 compared with 4.2 ± 6.5% across MD4). Respiratory symptoms followed a similar pattern to that of FEV1. Although the concentration of neutrophils in BAL after the MD4 exposure was not significantly different from that after the single-day exposure (1.7 ± 1.3 x 104 cells/ml vs. 1.2 ± 0.8 x 104 cells/ml, p = 0.20), the concentration of alveolar macrophages did significantly increase in BAL after the MD exposure (19.9 ± 9.7 x 104 cells/ml after MD4 vs. 12.1 ± 6.4 x 104 cells/ml after the single day). Conclusions: Alveolar macrophages are recruited to the airways of subjects with asthma with repeated short-term exposures to O3, suggesting a possible role for these cells in the chronic response to oxidant-induced injury.
Key Words: airway inflammation • alveolar macrophage • asthma • multiday exposure • ozone This article has been cited by other articles:
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