Inhibition of Lysosomal Degradation in Retinal Pigment Epithelium Cells Induces Exocytosis of Phagocytic Residual Material at the Basolateral Plasma Membrane

PURPOSE: To analyze chloroquine-induced morphological changes in the retinal pigment epithelium (RPE) and Bruch's membrane (BM). METHODS: Retina-choroid complexes of chloroquine-treated Long-Evans rats were analyzed by electron microscopy. RESULTS: Intercellular spaces between the RPE cells and BM were enlarged. Residual material from phagosomes was released into these enlarged spaces. Debris accumulated within BM and encircled choriocapillaris endothelial cells. CONCLUSION: There is a release of undegraded phagocytic material (rod outer segments) into the extracellular space between BM and RPE cells, following inhibition of lysosomal degradation. Electron-dense deposits in BM and choriocapillaris may lead to reduced oxygen and nutrition flow.