The effects of in vitro and aerosol exposures to cadmium on phagocytosis by rat pulmonary macrophages.

Aerosol exposures of rats were performed to assess the in vivo effects of cadmium on the phagocytosis of latex particles by pulmonary macrophages. An in vitro assay for particle uptake was devised which allowed quantification of phagocytosis by adhering and nonadhering macrophages. In vitro exposure to CdCl2 caused dose-dependent decreases in viability (trypan blue exclusion), percentage cells with particles, total number of particles phagocytized, and the ability of the macrophages to adhere to a siliconized glass surface. In vivo effects were studied following 30-min aerosol exposures to 1.5 mg/m3 Cd (MMAD = 0.35 micron, sigma g = 1.45) or 5.0 mg/m3 Cd (MMAD = 0.45 micron, sigma g = 1.60) as CdCl2. Phagocytic activity in the in vitro test system was increased immediately and at Day 1 in the low exposure group. However, following exposure to 5.0 mg/m3 Cd, phagocytic activity was depressed until 8 days postexposure. The results show that cadmium is capable of modifying the phagocytic ability of macrophages in vivo as well as in vitro. Determinations of the total number of particles phagocytized were found to be more sensitive than percentage cells phagocytizing in detecting the effects of cadmium exposure.