EFFECT OF HEAVY-METAL IONS ON THE RELEASE OF REACTIVE OXYGEN INTERMEDIATES BY BOVINE ALVEOLAR MACROPHAGES

Short-term incubations of bovine alveolar macrophages (BAM) with metal-containing dusts induce the release of reactive oxygen intermediates (ROI). Incubations of BAM (90 min) with dissolved metal compounds (0.1-100 mu M) combined with quartz dusts were performed to investigate the effects of single elements on BAM stimulation. As(III), as well as the calcium antagonists, Ni(II) and Ce(III), inhibited the secretion of superoxide anions (O-2(-)) and hydrogen peroxide (H2O2). O-2(-) concentrations were lowered by Mn(II) and Fe(II). Increased ROI concentrations were observed with V(IV) (O-2(-) and H2O2) and Fe(III) (O-2(-)) The addition of Cd(II), Cr(III) and V(V) showed no effect on the dust-induced respiratory burst. The influence of insoluble heavy metal compounds on ROI secretion by BAM were studied with metal oxide-coated silica particles. In most cases the release of ROI was not affected by the chemical modification of the particle surface, Coating with CuO markedly lowered the concentrations of O-2(-) and H2O2, whereas vanadium(IV) oxide considerably increased both ROIs. Although most of the investigated metal compounds did not alter ROI secretion our present results with V(IV) and Fe(III) confirm our recent statistical evaluation of the effects of heavy metal-containing dusts on ROI secretion (Berg et al., 1993, J. Toxicol. Environ. Health 39, 341).