Alteration of sialyl Lewis epitope expression in pterygium.
OBJECTIVE
Mucin-related antigens are abundantly expressed by the cells of the normal human conjunctiva. The pattern of these antigens in pterygium, and especially the role of Galbeta1-3GlcNAc alpha2,3-sialyltransferase (ST3Gal III), sialyltransferase necessary to build the sialyl-Le(a) (Lewis(a)) antigen, were studied.


METHODS
Immunoperoxidase staining was performed on 28 pterygia using different monoclonal antibodies: anti-M1 (against the peptidic core of gastric mucins encoded by MUC 5AC gene), anti-Le(a)(7LE), anti-sialyl Le(a)(NS 19-9), and anti-Le(b)(2-25LE). A serologic Lewis determination was done in 18 patients. ST3Gal III sialyltransferase expression was also studied in 10 healthy conjunctiva and 10 pterygia by reverse transcriptase-polymerase chain reaction (RT-PCR). Glyceraldehyde-3-phosphate-dehydrogenase was used as an endogenous internal control.


RESULTS
First, Le(a), sialyl Le(a), and Le(b) immunoreactivities either decreased or were no longer detectable in pterygium goblet cells as opposed to normal conjunctiva. Second, unlike in pterygium, the Lewis immunoreactivity, which is mainly located in the surface epithelial cells in the normal conjunctiva, was occasionally restricted to the epithelial cells of the deep layers. However, M1 mucins did show an identical pattern expression in a normal conjunctiva and pterygium. ST3Gal III expression was significantly lower in pterygium (0.20+/-0.02 AU [arbitrary units]) than in normal conjunctiva (0.95+/-0.12 AU).


CONCLUSIONS
ST3Gal III gene is less expressed in pterygium than in normal conjunctiva. This observation could explain the decrease of sialyl Le(a) expression observed in pterygium by immunohistology.
Department of Ophthalmology, University of Burgundy, Dijon, France.
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Creuzot-Garcher
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Guerzider
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Assem
A M
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Bron
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Delannoy
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Bara
D000017:ABO Blood-Group System / Q000378:metabolism; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal; D018395:CA-19-9 Antigen; D003228:Conjunctiva / Q000166:cytology / Q000378:metabolism; D017931:DNA Primers / Q000737:chemistry; D000939:Epitopes / Q000378:metabolism*; D005732:Gangliosides / Q000378:metabolism; D006801:Humans; D007124:Immunoenzyme Techniques; D007983:Lewis Blood Group Antigens / Q000378:metabolism*; D008875:Middle Aged; D009077:Mucins / Q000378:metabolism*; D010641:Phenotype; D011625:Pterygium / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012799:Sialyltransferases / Q000235:genetics / Q000378:metabolism*; D000094663:beta-Galactoside alpha-2,3-Sialyltransferase
D000017:ABO Blood-Group System; D000911:Antibodies, Monoclonal; D018395:CA-19-9 Antigen; D017931:DNA Primers; D000939:Epitopes; D005732:Gangliosides; D007983:Lewis Blood Group Antigens; D009077:Mucins; D012333:RNA, Messenger; C064564:sialyl Le(a) ganglioside; D012799:Sialyltransferases; D000094663:beta-Galactoside alpha-2,3-Sialyltransferase; C000722087:ST3GAL1 protein, human