[The chemotactic behavior of alveolar macrophages and blood monocytes after exposures to different NO2 concentrations]

The chemotaxis of alveolar macrophages (AM) and blood monocytes (BM) is important in the elimination of particles and microorganisms which have invaded the lung. The effect of nitrogen dioxide (NO2) on chemotaxis was tested on AM obtained by diagnostic bronchoscopy from five patients suspected of having bronchial carcinoma (four men, one woman; mean age 59 +/- 10 years). Blood monocytes were also studied with blood from seven healthy subjects (five men, two women; mean age 32 +/- 10 years). These cells were placed on polycarbonate membranes for 15 min each, exposed to NO2 concentrations between 1.0 and 5.0 parts per million (ppm), and then incubated with complement component C5a as chemotactically active agent. The number of AM or BM which actively migrated through the polycarbonate membrane under the influence of C5a was measured by means of a light microscope. The migration rate of AM (compared to air exposure) was reduced by 33% with 1.0 ppm NO2 and by 61% with 5.0 ppm. The migration rate of BM in similar conditions was reduced by as much as 55%. There was no significant cytotoxic effect of NO2 exposure at 1.0 and 3.0 ppm. With 5.0 ppm 13.0 +/- 3.0 cells were no longer viable. These results indicate that NO2 concentrations relevant to indoor conditions affect the chemotaxis of AM and BM after short-time NO2 exposures. The data further suggest that NO2 exposures of these cells depressed chemotactic mechanisms without relevant cytotoxicity.