Cigarette smoke exposure facilitates allergic sensitization in mice

Abstract

Abstract Background Active and passive smoking are considered as risk factors for asthma development. The mechanisms involved are currently unexplained. Objective The aim of this study was to determine if cigarette smoke exposure could facilitate primary allergic sensitization. Methods BALB/c mice were exposed to aerosolized ovalbumin (OVA) combined with air or tobacco smoke (4 exposures/day) daily for three weeks. Serology, lung cytopathology, cytokine profiles in bronchoalveolar lavage fluid (BALF) and on mediastinal lymph node cultures as well as lung function tests were performed after the last exposure. The natural history and the immune memory of allergic sensitization were studied with in vivo recall experiments. Results Exposure to OVA induced a small increase in OVA-specific serum IgE as compared with exposure to PBS (P + T-lymphocytes along with a marked increase in IL-5 measured in the supernatant of lymph node cell cultures. Immune memory experiments evidenced the transient nature of these phenomena. Conclusion In this study we show that mainstream cigarette smoke temporary disrupts the normal lung homeostatic tolerance to innocuous inhaled allergens, thereby inducing primary allergic sensitization. This is characterized not only by the development of persistent IgE, but also by the emergence of an eosinophil rich pulmonary inflammatory reaction.