The HNK-1 epitope in the inner connective tissue layer of the human ciliary body in exfoliation syndrome and various types of glaucoma.

Possible changes in the expression of the HNK-1 carbohydrate epitope in the inner connective tissue layer of the human ciliary body, located between the ciliary epithelium and muscle, was studied using 2 formalin-fixed, paraffin-embedded eyes with exfoliation syndrome, 33 eyes with different types of glaucoma, and 21 morphologically normal control eyes. A strong immunoreaction delineating cell process was observed in this layer with monoclonal antibodies HNK-1 and VC1.1 recognizing the HNK-1 epitope in control specimens, whereas partly granular immunoreaction was present in eyes with exfoliation syndrome. Exfoliation material was also immunoreactive. In all types of advanced glaucoma, the immunoreaction was mostly granular in nature and greatly diminished. No difference in HNK-1 immunoreactivity between control and glaucoma eyes was seen in the retina and ciliary epithelium. Elevated intraocular pressure, either directly or by decreasing blood flow to the ciliary body, may cause degenerative or metabolic changes in the inner connective tissue layer cells that bear or secrete molecules sharing the HNK-1 epitope. The partly granular immunoreactivity in eyes with exfoliation syndrome only indicates changes in this epitope even without an increase in intraocular pressure.