Cytotoxicity of dust constituents towards alveolar macrophages: interactions of heavy metal compounds.

The interactions between different heavy metal compounds which affect their cytotoxicity towards rabbit alveolar macrophages were investigated. The cells were exposed in vitro to combinations of As3+, Cd2+, Hg2+, Ni2+, or V5+ with different concentrations of another heavy metal compound. Toxicity was determined as the depression of zymosan-induced release of superoxide anion radicals. Significant antagonisms occurred in the combinations Cd2+/Zn2+, Hg2+/As3+, and Hg2+/Se4+, while significant synergisms were exhibited by the combinations Cd2+/Cu2+, Cd2+/Sn2+, Hg2+/Cu2+, Ni2+/Cd2+, Ni2+/Cu2+, Ni2+/Sn2+ and V5+/Cu2+. In the combinations As3+/Zn2+, Hg2+/Cd2+ and Hg2+/Zn2+, both kinds of interactions were observed depending on the concentrations of the heavy metal compounds. An interpretation of the measured heavy metal interactions with reference to the toxicity of heavy metal-containing dusts is attempted.