Mainstream cigarette smoke exposure attenuates airway immune inflammatory responses to surrogate and common environmental allergens in mice, despite evidence of increased systemic sensitization.

The purpose of this study was to investigate the impact of mainstream cigarette smoke exposure (MTS) on allergic sensitization and the development of allergic inflammatory processes. Using two different experimental murine models of allergic airways inflammation, we present evidence that MTS increased cytokine production by splenocytes in response to OVA and ragweed challenge. Paradoxically, MTS exposure resulted in an overall attenuation of the immune inflammatory response, including a dramatic reduction in the number of eosinophils and activated (CD69+) and Th2-associated (T1ST2+) CD4 T lymphocytes in the lung. Although MTS did not impact circulating levels of OVA-specific IgE and IgG1, we observed a striking reduction in OVA-specific IgG2a production and significantly diminished airway hyperresponsiveness. MTS, therefore, plays a disparate role in the development of allergic responses, inducing a heightened state of allergen-specific sensitization, but dampening local immune inflammatory processes in the lung.