The association of phagocytosed asbestos dust with lysosome enzymes

Granulomas were produced by the intrapleural injection of chrysotile asbestos dust (25 mg) into the right lower thoracic cavity of guineapigs. Animals were killed at 2 and 4 weeks after injection. Pieces of the granulomas were fixed and sectioned for electron microscopic examination, histochemical methods being used to stain for acid phosphatase. The Gomori technique reveals the presence of acid phosphatase as deposits of lead phosphate.
Acid phosphatase was demonstrated only in the lysosome series of organelles but not all of these structures gave a positive reaction. Usually less than 50%, of the lysosomes in the macrophages and giant cells gave a positive reaction and often fewer than 10% of the phagocytosed dust particles were in structures that gave a positive reaction. The few fibroblasts in the granulomas usually contained a small amount of chrysotile dust and then both primary lysosomes and dust-containing phagosomes usually contained acid phosphatase. There was no satisfactory evidence for the rupture of phagosomes and subsequent liberation of the Jysosomal enzymes into the cell cytoplasm. P. F. Holt.