Low level chromium (VI) inhalation effects on alveolar macrophages and immune functions in Wistar rats

In inhalation chambers, 5-week-old male Wistar rats of the strain TNO-W-74 were continuously exposed to submicron aerosols of sodium dichromate in concentrations from 25 (low level) to 200 g/m³ Cr (high level). Subacute exposure (28 days) to 25 and 50 g/m³ Cr resulted in activated alveolar macrophages with stimulated phagocytic activities, and significantly elevated antibody responses to injected SRBC's. After subchronic (90 days) low level exposure there was a more pronounced effect on activation of the alveolar macrophages, with increased phagocytic activities. However, at high Cr (VI) exposure level (200 g/m³), inhibited phagocytic function of the alveolar macrophages was seen. In rats which were exposed to this chromium aerosol concentration for 42 days, the lung clearance of inert iron oxide was reduced significantly. The humoral immune system was still stimulated at subchronic low chromium aerosol concentrations of 100 g/m³, but significantly depressed at 200 g/m³ Cr. These results show that respiratory defence and immunologic functions were stimulated or inhibited depending on dose and time of chromium (VI) inhalation.This paper was presented in part at the International Seminar on the Immunological System as a Target for Toxic Damage, November 6–9, 1984, Luxembourg