Expression of Sialyl Lewis X and Lewis X on the trabecular meshwork and conjunctiva of normal and glaucomatous eyes

Purpose. Sialyl Lewis X (SLe^x) and Lewis X (Le^x) are carbohydrate ligands which are expressed by specific cell types and are important in cell-cell interactions. This study attempts to determine the expression of SLe^x and Le^x on the trabecular meshwork (TM) and conjunctiva of both normal and glaucomatous eyes. Methods. Frozen anterior segment sections of human cadaver and rabbit eyes, as well as human cell cultures of normal and glaucomatous TM and corneal epithelia were stained with a panel of mAbs to neolacto-glycoconjugates using an Avidin-Biotin-Peroxidase Complex/alkaline phosphate staining method. Results. Rabbit TM sections were positive for SLe^x. In contrast, normal and glaucoma human TM sections did not stain for SLe^x or Le^x. However, SLe^x did have characteristic staining of both human conjunctival and corneal epithelia in normal (n=4) and glaucomatous (n=4) sections. SLe^x appeared to stain corneal and conjuctival epithelia of glaucomatous eyes much more intensely than normal. Rabbit cornea sections stained for both SLe^x and Le^x. Normal human TM cells in culture did not stain for SLe^x or Le^x. Glaucomatous TM cells showed light staining for SLe^x. Human corneal cells did stain for SLe^x.Conclusions. Distinct species specific differences were noted in SLe^x staining patterns for normal TM. While rabbit TM expressed glycoconjugates with SLe^x side chains, neither normal nor glaucomatous human TM reacted positively with anti-SLe^x mAbs. The expression of glycoconjugates wilh SLe^x side chains appears to be upregulated in the corneal and conjuctival epithelia of glaucomatous eyes. American Health Assistance Foundation and the Glaucoma Foundation.