Phagocytosis and chemotaxis of rat alveolar macrophages after a combined or separate exposure to ozone and carbon black.

Male Wistar rats were treated by ozone or carbon black (CB) alone as well as in combination. Intratracheal instillation with various amounts of CB was followed either by an acute 7-day or subchronic 2-month ozone exposure (0.5 ppm). Two functional parameters were investigated in alveolar macrophages from bronchoalveolar lavagates, the phagocytotic capacity and the chemotactic migration capability. In the phagocytosis assay, the percentage of phagocytizing macrophages decreased significantly in the CB-exposed groups whereas the ozone groups remained close to or at the control level after 7 days and 2 months of exposure, respectively. The number of ingested particles per macrophage and the formation of superoxide anion radicals were not changed after a 7-day exposure to ozone compared to the control group but were increased after a 2-month ozone exposure. However, a reduction was found in the CB groups. A stimulating effect of ozone was observed in the combined groups. Chemotactic migration was generally retarded in the CB-treated groups. From the results it can be concluded that ozone is able to stimulate the phagocytotic and chemotactic activity of alveolar macrophages whereas CB impairs these functions.