Degradation of phagosomes and diurnal changes of lysosomes in rabbit retinal pigment epithelium.

Kim,  In Taek; Kwak,  Jung Sik

doi:1996.10.2.82

Korean J Ophthalmol > Volume 10(2); 1996 > Article

Research Support, Non-U.S. Gov't

Korean Journal of Ophthalmology 1996;10(2):82-91.
DOI: https://doi.org/10.3341/kjo.1996.10.2.82 Published online December 30, 1996.

Degradation of phagosomes and diurnal changes of lysosomes in rabbit retinal pigment epithelium.

In Taek Kim, Jung Sik Kwak

¹Department of Ophthalmology, Kyungpook National University Hospital, Taegu, Korea.
²Department of Pathology, Kyungpook National University Hospital, Taegu, Korea.

Abstract

Diurnal changes of lysosomes including ultrastructural changes of phagosomes and acid phosphatase reactions in phagosomes, as well as diurnal biochemical changes in cathepsin D activity, were studied in the retinal pigment epithelium (RPE) of the rabbit. The rabbit was maintained on a natural light-dark cycle over seven days in fall and was sacrificed at various times during the day and night. The number of lysosomes or phagosomes in the RPE was the highest at 1.5 hours after exposure to sunlight (8:00 AM), and thereafter decreased with time. Three types of phagosomes were observed and acid phosphatase reactions were different in each type of phagosome; the fresh phagosomes were negative or positive, lamellar bodies positive, and dense bodies partially positive. The biochemical activity of cathepsin D was the highest at 8:00 AM, and this was consistent with the time of peak in phagocytic activity in the RPE. This report shows that phagocytic activity in the RPE occurred in the early stage after exposure to sunlight, and that fresh phagosomes were sequentially degraded to lamellar or dense bodies. Cathepsin D activity also increased, and this was consistent with the phagocytic activity in the RPE.

Key Words: acid phosphatase;cathepsin D;diurnal change;Iysosome;phagosome;retinal pigment epithelium (RPE)