The endocytosis of asbestos by mouse peritoneal macrophages and its long-term effect on iron accumulation and labyrinth formation.

The effect of a single intraperitoneal injection of crocidolite asbestos fibres on the peritoneal cell population were studied. Attention was paid to the changes in the proportions taken by the various types of cell in this population after peritoneal stimulation as well as the handling of asbestos fibres by the peritoneal cells and the formation of asbestos bodies. Intraperitoneal administration of crocidolite led to an influx of inflammatory cells into the peritoneal cavity. The asbestos fibres were phagocytosed and gradually cleared from the peritoneal cavity. Long before this clearance was completed, the peritoneal cell population had returned to the steady state. The stimulated peritoneal macrophages showed increasing concentrations of iron in both lysosomes and the cytoplasm. At later time points, residual bodies containing iron and asbestos fibres were seen frequently in macrophages, but asbestos bodies were not found. As a reaction to the administration of crocidolite asbestos, macrophages from the peritoneal cavity develop tubular systems (labyrinths) that increase in number and size.