Second-hand smoke is an adjuvant for T helper-2 responses in a murine model of allergy.

Epidemiologic studies have suggested that "second-hand smoke" increases the incidence and severity of allergies and asthma. To address this, we developed a murine model that included generation of and exposure to environmental tobacco smoke (ETS) followed by aerosolized Ag challenge. We report herein that exposure of OVA-sensitized BALB/c mice to ETS elicits a rapid and prolonged exaggerated response with respect to IgE, IgG1, eosinophils, and Th2 cytokines (particularly IL-4 and IL-10). There was a significant increase (p = 0.0159) in the total cells of the bronchoalveolar lavage in OVA-sensitized mice exposed to ETS when compared with those in ambient air. This is the first experimental data to demonstrate that "second-hand smoke" up-regulates the allergic response to inhaled Ag. The results have important health implications for children and allergic individuals residing in households with smokers.