Rationale: Epidemiologic studies suggest that tobacco smoke contributes to the prevalence and occurrence of exacerbations in asthma. The effect of active smoking in adolescents with atopy is poorly understood.
Objectives: We developed an experimental model to investigate the influence of smoking on antigen-induced airway inflammation and airway responsiveness in mice that were previously sensitized.
Methods: Ovalbumin (OVA)-sensitized BALB/c mice were exposed to air or mainstream smoke (5 days/week) and to phosphate-buffered saline (PBS) or OVA aerosol (3 times/week) for 2 weeks (n = 8 for each group).
Results: Airway responsiveness to intravenously injected carbachol was increased (p < 0.05) in smoke- and OVA-exposed mice compared with all other groups. There was an additive effect of smoke and OVA exposure on total cell numbers, macrophages, and dendritic cells in bronchoalveolar lavage fluid and on CD4+ and CD8+ T lymphocytes and dendritic cells in lung tissue (p < 0.05 compared with mice exposed to smoke and PBS and to mice exposed to air and OVA). Concurrent smoke and OVA exposure augmented OVA-specific IgE in serum compared with air and OVA exposure. In lavage fluid supernatant, eotaxin was increased in air- and OVA-exposed mice. The further increase observed in the group exposed to both OVA and cigarette smoke came close to formal significance (p = 0.06). Thymus- and activation-regulated chemokine was augmented in mice exposed to either smoke or OVA, without additional effect.
Conclusions: Our data indicate that acute concurrent exposure to allergen and mainstream cigarette smoke enhances airway inflammation and airway responsiveness in previously sensitized mice.