DIESEL EXHAUST ENHANCES ALLERGIC AIRWAY INFLAMMATION AND HYPERRESPONSIVENESS IN MICE

We previously reported that the intratracheal instillation of diesel e xhaust particles enhances allergic airway inflammation and hyperrespon siveness in mice. However, it is not known whether the effects of such instillation differ from those obtained with the daily inhalation of diesel exhaust. We therefore examined whether the inhalation of diesel exhaust would also enhance allergic reactions. Mice were exposed to d iesel exhaust or clean air for 5 wk. After the first week, the animals were sensitized to ovalbumin by intraperitoneal injection. At the end of the exposure period, they underwent an ovalbumin challenge. Contro l animals received saline instead of ovalbumin. Independently of ovalb umin sensitization, diesel exhaust caused an increase in the numbers o f neutrophils and macrophages in bronchoalveolar lavage fluid, whereas a significant increase in eosinophil numbers occurred only after anti gen challenge combined with diesel exhaust exposure. Furthermore, oval bumin alone caused an increase in eosinophil numbers in lung tissue, a nd this was enhanced by diesel exhaust. Exposure to diesel exhaust com bined with ovalbumin sensitization, but not diesel exhaust inhalation alone, enhanced the number of goblet cells in lung tissue, respiratory resistance, production of ovalbumin-specific immunoglobulin E and G(1 ) in the serum, and expression of interleukin-5 in lung tissue.