Evaluation of methods for specific loading of Kupffer cell lysosomes with heavy colloidal particles.

Abstract

The purpose of this electron microscopic study was to analyze the possibility to achieve a selective uptake of heavy macromolecules in Kupffer cell lysosomes of rat liver in order to create a basis for attempts aiming at isolating Kupffer cell lysosomes by way of ultra‐centrifugational techniques. Intravenous injections of colloidal solutions of thorium dioxide and silver iodide were employed for this purpose. The results showed that typical thorium dioxide macromolecules (70–200 Å large) appeared in the vacuolar apparatus of both Kupffer and parenchymal cells early after the injection. On the other hand, aggregates of silver iodide macromolecules (200–1,300 Å large) were only encountered in the Kupffer cells, and became concentrated in the lysosomes of these cells during the first hour after intravenous administration. Disappearance of the large granular silver iodide compound occurred between 12 and 24 hours post‐injection. The evidence suggested that this was due to disaggregation of the macromolecules into single silver iodide units capable of escaping through intact lysosomal membranes. These small molecules might—in part—be transferred to the lysosomes of the parenchymal cells. It was concluded that pretreatment of rats with an intravenous injection of colloidal silver iodide (Neosilvol®) should be a useful approach to achieving the isolation of Kupffer cell lysosomes, provided the fractionation was performed approximately 60 minutes after the administration.