Novel expression and characterization of lymphatic vessel endothelial hyaluronate receptor 1 (LYVE-1) by conjunctival cells

PURPOSE: Lymphatic vessel endothelial hyaluronic acid receptor (LYVE-1) is a newly discovered lymphatic-specific marker. To date, there is no report of its expression on conjunctival cells. The purpose of this study was to investigate the expression of LYVE-1 in normal conjunctiva, to phenotype LYVE-1+ cells, and to study changes in their expression levels during corneal inflammation. METHODS: Flat-mounted conjunctivae or cross sections of eyeballs were harvested from BALB/c mice (6-8 weeks of age) for immunofluorescent confocal microscopic studies. RESULTS: The data demonstrate, for the first time, that in addition to its expression on lymphatic vessels, LYVE-1 was expressed on CD45+, CD11b+, and CD31- conjunctival cells, indicating a bone-marrow-derived monocytic lineage. Surprisingly, the number of cells that expressed LYVE-1 decreased during corneal inflammation, in conjunction with ingrowth of lymphatics into the cornea. CONCLUSIONS: A new population of monocytic cells has been found to express LYVE-1 in normal conjunctiva. These cells that normally express LYVE-1 may act as a reservoir for lymphangiogenesis and cell recruitment when the immune system is challenged.