CHEMOTACTIC RESPONSE OF HUMAN ALVEOLAR MACROPHAGES AND BLOOD MONOCYTES ELICITED BY EXPOSURE TO SULFUR-DIOXIDE

An experimental study was undertaken to investigate the in vitro effec t of sulfur dioxide on the chemotactic activity of alveolar macrophage s (AM) and blood monocytes (BM). The cells were placed on a polycarbon ate membrane and exposed to SO2 0.5, 1.5 and 2.5 ppm for 15 min. Contr ol experiments were performed with exposure of the cells to synthetic air with 5% CO2. After gas exposure the cells were incubated with the chemotactic active agent C5a in 5% carbon dioxide (CO2) at 37 degrees C for 60 min. The numbers of AM and BM passing actively through the me mbrane were quantified using light microscopy. Our results show a dose -dependent reduction in the migration rate of cells under SO2 exposure . SO2 0.5 ppm induced a 29% and SO2 2.5 ppm a 53% decrease in migratio n of AM compared with the control exposure to synthetic air (P < 0.01) . Identical experiments with BM resulted in a decrease in migration of up to 57% (P < 0.01). At SO2 concentrations of up to 2.5 ppm no signi ficant cytotoxic effects were observed for AM or BM. The data demonstr ate that exposure to SO2 may reduce the chemotactic activity of AM and BM. Our results further suggest that the decrease in cell migration i nduced by SO2 is due to changes in chemotactic mechanisms and not to c ell death.