Generation and characterization of antibodies to adhesion-related molecules of retinal pigment epithelial cells.

We have generated antisera to pig retinal pigment epithelial (RPE) cells and to their fractionated membrane proteins. The antisera have been screened functionally by adhesion inhibition assays, and morphologically with immunofluorescence microscopy of cultured cells and frozen sections of the retina. From these sera, we have affinity purified five monospecific antibodies to the RPE surface molecules having molecular weights of 220, 180, 110, 85 and 70 kDa, which effectively inhibit cell-substratum attachment. The 220 and 85 kDa antigens are localized to focal contacts of the cultured cells and are seen in patches in the intact RPE layer in frozen sections of eye tissues. Immunofluorescence microscopy shows that the 180, 110 and 70 kDa antigens localize predominantly to cell-cell junctions. Hence, these antigens may participate in both cell-cell and cell-substratum adhesion in RPE cells. Staining patterns obtained with confocal microscopy of frozen sections of the retina demonstrate that these antibodies are RPE-specific. These adhesion-related molecules may play a role in maintenance of the morphological and functional integrity of RPE.