Role of alveolar macrophages in precipitation of mineral elements inhaled as soluble aerosols.

The lysosomes of several varieties of cells such as the tubular proximal cell of the kidney and the alveolar macrophage have the ability to concentrate and precipitate several elements inhaled in water-soluble form, usually as phosphate. The mechanism involved is attributed to the high acid phosphatase activity of lysosomes and can be considered as an in vivo Gomori reaction. Among the elements studied, most of them are chemotoxic or radiotoxic (Cr; group IIIA: Al, Ga, In; rare earths: La, Ce, Tm; actinides: Th, U). In the lung macrophage, this mechanism of intralysosomal concentration and precipitation may prevent the diffusion of these toxic elements through the alveolar membrane.