ROLE OF ALVEOLAR MACROPHAGE LYSOSOMES IN METAL DETOXIFICATION

The intracellular behaviour of different toxic mineral elements inhale d as soluble aerosols or as insoluble particles was studied in the rat by electron microscopy, electron probe microanalysis, and electron mi crodiffraction. This study showed that, after inhalation, aerosols of soluble elements like cerous chloride, chromic chloride, uranyl nitrat e, and aluminium chloride, are concentrated in the lysosomes of alveol ar macrophages and are precipitated in the lysosomes in the form of in soluble phosphate, probably due to the activity of acid phosphatase (i ntralysosomial enzyme). Also, after inhalation of crystalline particle s that are insoluble or poorly soluble in water such as the illites (p hyllosilicates), eerie oxides (opaline), and industrial uranium oxides (U3O8), the small crystals are captured by the alveolar macrophage ly sosomes and transformed over time into an amorphous form. This structu ral transformation is associated with changes in the chemical nature o f particles inhaled in the oxide form. Microanalysis of amorphous depo sits observed after inhalation of uranium or eerie oxides has shown th at they contain high concentrations of phosphorus associated with the initial elements cerium and uranium. These different processes tend to limit the diffusion of these toxic elements within the organism, whet her they are inhaled in soluble form or not. (C) 1997 Wiley-Liss, Inc.