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Polydispersity of normal human conjunctival mucins
M Berry1, R B Ellingham, A P Corfield
1Department of Ophthalmology, University of Bristol, Bristol Eye Hospital, United Kingdom.
Investigative Ophthalmology & Visual Science
|December 1, 1996
Summary
Human conjunctival mucins were isolated and characterized. These mucins contain unique oligosaccharide patterns, including Tn and sialyl-Tn antigens, suggesting normal roles in ocular health.
Area of Science:
- Biochemistry
- Glycobiology
- Ocular Surface Science
Background:
- Mucins are crucial glycoproteins in the ocular surface, providing lubrication and protection.
- Understanding the composition of conjunctival mucins is essential for diagnosing and treating ocular surface diseases.
- Tumor-related antigens like Tn and sialyl-Tn have been identified in various cancers, but their role in normal ocular tissues is less understood.
Purpose of the Study:
- To isolate and characterize the constituent mucins present in human conjunctival mucus.
- To investigate the oligosaccharide composition of these mucins, specifically looking for tumor-related antigens.
- To determine the potential normal role of these antigens in the human ocular surface.
Main Methods:
- Human conjunctival mucus was extracted using guanidine hydrochloride and protease inhibitors.
- Mucins were purified through density gradient centrifugation, gel filtration, and ion exchange chromatography.
- Purification was monitored using agarose electrophoresis and vacuum blotting, with blots probed for peptide and carbohydrate epitopes, including IE3 and TKH2 (specific for Tn and sialyl-Tn).
Main Results:
- Human conjunctival mucins exist in at least three size populations, with the largest excluded on Sepharose CL2B.
- Electrophoretic patterns and charge distributions were conserved across individuals and different buoyant density ranges.
- The mucins showed cross-reactivity with IE3 and TKH2, indicating the presence of Tn and sialyl-Tn antigens, particularly in larger mucins and impression cytology specimens.
Conclusions:
- Secreted human conjunctival mucins are polydisperse with consistent components across samples.
- A unique oligosaccharide pattern containing Tn and sialyl-Tn was identified in these mucins.
- This suggests a normal physiological role for Tn and sialyl-Tn antigens in human ocular mucins, distinct from their association with disease in other tissues.