Reaction of pulmonary macrophages exposed to nickel and cadmium in vitro.

We examined the morphological and functional characteristics of goat alveolar macrophages exposed in a serum-free medium in vitro for up to 20 hr to cadmium as CdCl2 and nickel as NiCl2. The concentration of these metals varied from 0.04 to 1.00 mM. Cadmium reduced the viability and phagocytosis of macrophages and increased the release of lactate dehydrogenase from cells into the culture medium at all the concentrations tested. Alterations in macrophage surface morphology, evaluated by scanning electron microscopy, consisted of withdrawal of pseudopodia and rounding of cells exposed to 0.20 and 1.00 mM of CdCl2. In nickel-exposed macrophages these changes were marked only at higher concentrations of the metal. Higher concentrations of Ni were necessary to produce effects similar to those produced by lower Cd concentrations. Our results demonstrated that the higher toxicity of cadmium as compared to that of nickel for alveolar macrophages is related to a difference in the alterations in the morphology and function of the exposed cells.