CYTOKINE PRODUCTION BY RETINAL PIGMENTED EPITHELIAL-CELLS

This chapter discusses cytokine production by retinal pigmented epithelial cells. The retinal pigmented epithelium (RPE) has many functions through which it assists the photoreceptors in visual transduction. In addition to the well-recognized day-to-day maintenance functions, the RPE also plays a very active role in normal and pathologic retinal-wound healing. RPE is normally mitotically inactive and undergoes cell division only when it is participating in wound healing. The adult human RPE does not readily achieve density-dependent growth arrest when cultured on plastic and even when serum is withdrawn, it continues to grow. These observations suggest that under certain conditions, cultured human RPE may simulate the wound healing phenotype of RPE in situ and provide a useful tool to study this aspect of RPE function. These observations also suggest that RPE cells may be able to stimulate their own growth. The RPE conditioned media is capable of stimulating the growth of RPE and several other cell types, indicating that cultured RPE may produce one or more cytokines and secrete them into their media. The growth-promoting activity in RPE-conditioned media is found to be trypsin-sensitive and a portion of it is heat-stable. © 1993, Academic Press Inc.