PLATELET-DERIVED GROWTH-FACTOR LIGANDS AND RECEPTORS IMMUNOLOCALIZED IN PROLIFERATIVE RETINAL DISEASES

Purpose. Platelet-derived growth factor (PDGF) and its receptors could contribute to the development of proliferative retinal membranes, bec ause PDGF is angiogenic and is both mitogenic and chemotactic for reti nal pigment epithelial (RPE) and glial cells, components of membranes. The authors sought to determine whether PDGF ligands and their recept ors were present in proliferative retinal membranes. Methods. To local ize PDGF ligands and receptors, the authors examined normal postmortem control retinas, intact eyes with proliferative vitreoretinopathy (PV R) or proliferative diabetic retinopathy (PDR), and membranes removed by vitrectomy from patients with PVR, epimacular proliferation, PDR, o r PVR with PDR of previous onset. Sections were stained with antibodie s specific for each PDGF ligand and receptor, using an avidin-biotin-c omplex immunohistochemical technique. To correlate PDGF receptor beta (PDGFR beta) and ligand immunostaining, sections were double labelled with antibodies specific for either PDGF-A or PDGF-B. Results. Ligands . In the normal retina and choroid, staining for the A-chain was limit ed to vascular cells. Only the nerve fiber layer and vessels were posi tive for the B-chain. In diseased tissue, PDGF-A immunoreactivity was detected as intense staining (+++) of all but one of the proliferative retinal membranes; some RPE cells were positive for PDGF-A, especiall y in the eye with PDR. PDGF-B was also present in many proliferative r etinal membranes but not in RPE cells. Receptors. In the normal retina and choroid, both PDGFR alpha and PDGFR beta were detected only in ve ssels. In proliferative retinal membranes, both receptors were detecte d in vessels. Long strands of RPE-like cells at the edges of PVR membr anes were strongly positive for PDGFR beta but negative or +/-, respec tively, for PDGFR alpha. Double-label assays showed that PDGFR beta wa s often colocalized with each PDGF ligand, especially in pigmented cel ls. Conclusions. PDGF ligands and receptors are widespread in prolifer ative retinal membranes of different origin. Because PDGFR beta and PD GF-B were colocalized in many of the same cells, the potential for aut ocrine and paracrine stimulation of cell migration and growth exists. These results are consistent with a role for PDGF ligands and receptor s in the pathogenesis of different proliferative retinopathies.