HNK-1 epitope in the lens-ciliary zonular region in normal and pseudoexfoliative eyes. Immunohistochemistry and ultrastructure
Y. Qi, B. W. Streeten and R. N. Wallace
Department of Ophthalmology, State University of New York Health Science Center at Syracuse, USA.
OBJECTIVE: To determine the specific binding sites for the HNK-1 adhesion
molecule epitope in the lens-ciliary zonular region in normal and
pseudoexfoliative (PSX) eyes. METHODS: Normal and PSX eyes and adjacent
tissues from individuals aged 10 months to 89 years were investigated for
the HNK-1 epitope by immunohistochemistry and immunogold electron
microscopy. RESULTS: Concentration of HNK-1 epitope was high in the
anterior central lens capsule into old age, but it tapered earlier and
progressively in the inner capsule and elsewhere. On zonular fibers, label
was strongest at their lens and ciliary attachments and intense on related
elastic microfibrils in adjacent ciliary stroma. Label was also strong on
PSX fibers and above normal on PSX central capsule. In contrast, HNK-1 was
absent on PSX aggregates in conjunctiva and skin and on normal elastic
microfibrils in these tissues. CONCLUSIONS: The prominent HNK-1 epitope in
lens capsule and zonule has age- and site-specific variations that favor
adhesive roles in each. The high density of epitope on ocular PSX material
suggests an aberrant increase in expression that may contribute to
adhesiveness of these aggregates, HNK-1 negativity on extraocular elastic
microfibrils and PSX aggregates indicates a unique difference in
composition of intraocular and extraocular elastic tissue, of potential
significance for ocular function in aging and lens-dislocating diseases.
