Identification of a novel element in the human eye: the inner connective tissue layer of the ciliary body characterized with antibodies to the HNK-1 epitope.
OBJECTIVE
To characterize the nature and the developmental distribution of the HNK-1 epitope in the inner connective tissue layer of the human ciliary body, located between the ciliary epithelium and muscle with two monoclonal antibodies to the HNK-1 epitope common to many cell adhesion molecules.


METHODS
Nine fetal (gestational age 13-40 wk) and 32 postnatal human eyes (age 3 mo to 78 yr) were studied by immunohistochemistry with monoclonal antibodies HNK-1 and VC1.1 to the HNK-1 epitope. Antibodies to cytoskeletal elements were used to characterize the cells in this region.


RESULTS
The HNK-1-immunopositive cells appeared underneath the pigment epithelium of the pars plicata by the 20th gestational week, spread into the pars plana after the 28th week, and reached the ora serrata during the first year of life. The immunoreaction was constantly present in all adult eyes examined; they were sharply demarcated from the iris, ciliary muscle, and choroid. The HNK-1-positive subepithelial layer was not labeled with monoclonal antibodies V9 or Vim 3B4 to vimentin, monoclonal antibodies CAM 5.2 and CY-90 to cytokeratin 8 and 18, or monoclonal antibodies DE-U-10 and D33 to desmin in adult eyes, but was uniformly positive for vimentin in fetal eyes. The HNK-1 epitope was distributed along cell membranes or adjacent extracellular matrix of stromal cells.


CONCLUSIONS
The HNK-1-positive stromal region is a constant and conspicuous element of the human eye that may have a role in structurally stabilizing the ciliary body, perhaps in relation to accommodation or aqueous secretion.
Uusitalo
M
M
Department of Ophthalmology, Helsinki University Central Hospital, Finland.
Kivelä
T
T
Tarkkanen
A
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000276:immunology; D000943:Antigens, Differentiation / Q000276:immunology / Q000378:metabolism*; D018959:CD57 Antigens; D002648:Child; D002675:Child, Preschool; D002924:Ciliary Body / Q000196:embryology / Q000378:metabolism*; D003238:Connective Tissue / Q000196:embryology / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000276:immunology / Q000378:metabolism; D000939:Epitopes / Q000276:immunology / Q000378:metabolism*; D005136:Eye Proteins / Q000276:immunology / Q000378:metabolism; D005333:Fetus; D006801:Humans; D007124:Immunoenzyme Techniques; D007223:Infant; D008875:Middle Aged; D010857:Pigment Epithelium of Eye / Q000276:immunology / Q000378:metabolism
D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation; D018959:CD57 Antigens; D003598:Cytoskeletal Proteins; D000939:Epitopes; D005136:Eye Proteins