Lysosomal involvement in beryllium phosphate toxicity.

The fate of i.v. administered particles of beryllium phosphate (50 mumol/kg) has been investigated by electron microscopy in the liver of the rat. These particles were endocytosed by the Kupffer cells within 15 min of administration but they were never found in the endothelial or parenchymal cells of the liver. Endocytosed particles were rapidly degraded within vesicles which were identified as secondary lysosomes. Pronounced swelling of these lysosomes subsequently developed, within 60 min of administration, resulting in distension of the entire cell. This vacuolation was entirely restricted to the Kupffer cells, particularly those in the pericanalicular region of the hepatic lobules. Lysosomal swelling, or even rupture, probably resulted in the subsequent death of these cells by the intra-cytoplasmic release of beryllium.