... numbers of villi, and is involved in phagocytosis of shed outer segments [1] and in uptake,processing, and transport of retinoids [2]. RPE alsoparticipates in absorption of light with its melanin ... , interferon-c has been shown to inhibit proliferation of parasites by inducin g the expression of indoleamine 2,3-dioxygenase, a heme-containing enzymethat converts tryptophan to kynurenine, ... HO-1gene through a certain protein factor in RPE cells. Theseresults indicate that RPE cells maintain retinal homeostasisby repressing or inducing the expression of HO-1, dependingon the microenvironment.Keywords:...