Aim of the study: To investigate the expression of three inflammation markers, HLA-DR, IL-6, and IL-8, by conjunctival epithelial cells obtained using impression cytology (IC) samples from long-term treated glaucoma patients.

Patients and methods: IC samples were obtained from the 60 following individuals: 45 patients suffering from primary open-angle glaucoma and receiving topical treatments for at least 1 year and 15 subjects with no ophthalmological disease (controls). Membrane expression of HLA-DR and intracellular expression of IL-6 and IL-8 were quantified, respectively, by indirect and direct immunofluorescence techniques. Fluorescence levels were quantified using calibrated fluorescent beads.

Results: The percentage of HLA-DR-positive cells was significantly higher on IC samples from multitreated glaucoma patients and from patients treated by either preserved betablocker or preserved prostaglandin analogue than on IC samples from control individuals. Interestingly, the percentage of HLA-DR-positive cells was not significantly increased upon treatment with unpreserved betablocker. However, the percentage of IL-6- and IL-8-positive cells as well as IL-6 and IL-8 expression levels was significantly higher in patients than in controls, regardless of the treatment type and the presence of preservative. A significant positive correlation was found between HLA-DR and cytoplasmic IL-6 expression, between HLA-DR and cytoplasmic IL-8 as well as between IL-6 and IL-8 cytoplasmic expressions.

Conclusion: The present study confirms that there is an increased expression of HLA-DR in treated glaucoma patients compared to controls and demonstrates that antiglaucoma treatments lead to increased IL-6 and IL-8 expressions. It also indicates that benzalkonium-preserved eyedrops and preserved multitherapy may induce stronger inflammatory responses than do unpreserved eyedrops, although further studies are needed to determine the respective inflammatory role of preservative and therapeutic molecules. In this study, flow cytometry was used to detect the intracellular pro-inflammatory cytokines in conjunctival cells obtained by impression cytology. This standardized and reliable technique was a useful tool to assess inflammatory and allergic ocular surface disorders.