Allergic inflammation enhances bacterial sinusitis in mice

Background: Although it is not proven, one factor considered important in t he development of sinusitis is allergic rhinitis. Objective: The purpose of this study was to determine whether ongoing aller gic rhinitis enhances the infection and inflammation associated with Strept ococcus pneumoniae acute sinus infection. Methods: BALB/c mice were sensiti zed to ovalbumin by intraperitoneal injection. After infection of the sinus es by S pneumoniae, either with or without concomitant administration of ov albumin to induce allergic inflammation, mice were killed at various times and their heads were prepared for histologic evaluation of the sinuses. Results: Mice became allergic to ovalbumin and developed eosinophilia in th e sinus and lung cavities in response to ovalbumin administration to each o f the respective cavities. In comparison with controls, the mice with ongoi ng nasal allergic inflammation that were inoculated with S pneumoniae had s ignificantly more bacteria recovered at sacrifice and had significantly mor e inflammation, as indicated by neutrophil, eosinophil, and mononuclear inf lux into the sinus mucosa. The percentage of the sinus area occupied by neu trophil clusters was also increased after infection in the allergic mice in comparison with the control mice. Conclusion: Our data demonstrate that mice can be sensitized to ovalbumin a nd develop a localized allergic reaction in the skin, nose, or lung. An ong oing local allergic response augments bacterial infection in these animals. We also demonstrate that allergic sensitization alone, allergen exposure a lone, or an allergic response at a distal site, the lung, does not augment the sinus infection.