Ozone exposure enhances antigen-presenting activity of interstitial lung cells in rats.

Ozone (O(3)) as a major component of photochemical air pollutants can increase the levels of allergen-specific antibody and may aggravate allergic symptoms. Antigen presentation is one of the factors contributing to allergic symptoms. Our present study is designed to clarify whether O(3) may increase the antigen-presenting (AP) activity of whole lung cells and its mechanisms. Male Wistar rats were exposed to 1 ppm O(3) for 3 days. The AP activity of whole lung cells and dendritic cells (DC) was measured by proliferation of T-cells. The expression of Ia and costimulatory molecules (B7.1, B7.2, CD11b/c) in lung cells was measured by flow cytometry, and the number of Ia-bearing cells, DC, macrophages, and B-cells in lung interstitum was examined immunohistochemically. The results show that O(3) increases AP activity of whole lung cells and DC, the expression of molecules associated with antigen presentation, and the number of AP cells (APC) in lung. Our results suggest that O(3) may enhance AP activity of lung cells caused by increases in the expression of cell-surface molecules and the number of APC in lung. The increase in the AP activity might contribute to subsequent antibody production, airway hyperresponsiveness and aggravation of allergic responses.