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E.B. Cook, J.L. Stahl, F.M. Graziano, N.P. Barney; tnf Receptor Type I Expression on Human Conjunctival Epithelial Cells: Correlation With Icam-1 Expression . Invest. Ophthalmol. Vis. Sci. 2003;44(13):707.
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ICAM-1 expression on the ocular surface is a hallmark of ocular allergic inflammation and correlates with disease severity and evidence of eosinophil activation. We have previously demonstrated that IgE-activated mast cells upregulate ICAM-1 expression on conjunctival epithelial cells via a TNFα specific mechanism. Purpose: To examine the relationship between ICAM-1 expression and TNFRI (the receptor for soluble TNFα ) expression. Methods: Human conjunctival epithelial cells were enzymatically dispersed from multiple donor pools of cadaveric conjunctival tissues and cultured in 24 well plates on a fibronectin/collagen matrix. The cells were incubated with and without pro-inflammatory cytokines (TNFα , IL-1ß , IFNγ ) or IgE-activated mast cell supernates for 24 hours prior to harvesting with Trypsin-EDTA for analysis of ICAM-1 and TNFR1 receptor expression using two-color flow cytometry analysis. Results: As previously reported, ICAM-1 was expressed constitutively and upregulated by all three pro-inflammatory cytokines, most potently with IFNγ . Interestingly, TNFRI expression was detectable only on cells that were also ICAM-1 positive. Furthermore, ICAM-1 expression on TNFRI positive cells was 200-300 mean fluorescence intensity units greater than ICAM-1 expression on TNFRI negative cells. TNFα and IL-1ß had no effect on TNFRI expression. However, IgE activated mast cell supernates increased both TNFRI and ICAM-1 expression. In contrast, the percentage of ICAM-1 positive cells expressing TNFRI was decreased by IFNγ treatment. Conclusions: These results demonstrate coordinated expression of ICAM-1 and TNFRI on conjunctival epithelial cells, the latter of which is limited to a sub-population of cells, suggesting the existence of two distinctive populations of epithelial cells in these primary cultures.
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