CHEMOTAXIS OF ALVEOLAR MACROPHAGES AND BL OOD MONOCYTES AFTER EXPOSURE TO VARYING CONCENTRATIONS OF NITROGEN-DIOXIDE

The chemotaxis of alveolar macrophages (AM) and blood monocytes (BM) i s important in the elmination of particles and microorganisms which ha ve invaded the lung. The effect of nitrogen dioxide (NO2) on chemotaxi s was tested on AM obtained by diagnostic bronchoscopy from five patie nts suspected of having bronchial carcinoma (four men, one woman; mean age 59 +/- 10 years). Blood monocytes were also studied with blood fr om seven healthy subjects (five men, two women; mean age 32 +/- 10 yea rs). These cells were placed on polycarbonate membranes for 15 min eac h, exposed to NO, concentrations between 1.0 and 5.0 parts per million (ppm), and then incubated with complement component C5a as chemotacti cally active agent. The number of AM or BM which actively migrated thr ough the polycarbonate membrane under the influence of C5a was measure d by means of a light microscope. The migration rate of AM (compared t o 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 a s much as 55%. There was no significant cytotoxic effect of NO2 exposu re at 1.0 and 3.0 ppm. With 5.0 ppm 13.0 +/- 3.0 cells were no longer viable. - These results indicate that NO, concentrations relevant to i ndoor conditions affect the chemotaxis of AM and BM after short-time N O2 exposures. The data further suggest that NO2 exposures of these cel ls depressed chemotactic mechanisms without relevant cytotoxicity.