Vascular expression of endothelial antigen PAL-E indicates absence of blood-ocular barriers in the normal eye

Ophthalmic Res. 1997;29(3):130-8. doi: 10.1159/000268007.


The endothelium-specific antigen PAL-E is expressed in capillaries and veins throughout the body with the exception of the brain, where the antigen is absent from anatomical sites with a patent blood-brain barrier. In this study we determined vascular endothelial staining for PAL-E in the normal eye in relation to the ocular blood-tissue barriers. Immunohistochemical staining of frozen tissue sections of eyes from 22 cornea donors and a number of normal animal autopsy eyes was performed for the PAL-E antigen and the blood-brain barrier marker glucose transporter 1. In normal human and animal eyes, endothelial PAL-E staining was absent from the microvasculature in iris, ciliary muscle, optic nerve and retina. In a few normal human eyes, some weakly stained capillaries were observed in the retina and nerve fiber layer, mostly in the peripapillary area. Marked staining of capillaries and venules with PAL-E was observed in the conjunctiva, episclera, sclera, ciliary processes, choriocapillaris and optic nerve head. In general, the endothelial antigen PAL-E is absent from microvessels involved in the blood-ocular and the blood-retinal barriers. PAL-E may therefore be a useful marker to identify pathological breakdown of blood-ocular barriers.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Monoclonal
  • Antigens, Surface / immunology
  • Antigens, Surface / metabolism*
  • Arteries / metabolism
  • Biological Transport, Active
  • Cattle
  • Endothelium, Vascular / immunology
  • Endothelium, Vascular / metabolism*
  • Eye / blood supply*
  • Glucose Transporter Type 1
  • Humans
  • Immunoenzyme Techniques
  • Macaca fascicularis
  • Monosaccharide Transport Proteins / metabolism
  • Rabbits
  • Sheep
  • Swine
  • Veins / metabolism


  • Antibodies, Monoclonal
  • Antigens, Surface
  • Glucose Transporter Type 1
  • Monosaccharide Transport Proteins
  • SLC2A1 protein, human