Purpose: The aim of this work was to study, using flow cytometry, the expression of two chemokine receptors, CCR4 and CCR5, known to be related to the TH2 and TH1 systems, respectively, and the expression of HLA-DR, a hallmark of inflammation, on conjunctival impression cytology specimens (ICS) of glaucomatous patients treated over the long term.
Patients and methods: In this case-control study, ICS were taken in a series of 35 glaucomatous patients treated with topical antiglaucoma drugs for more than 1 year (seven with beta-blockers, ten with prostaglandins, and 18 receiving multiple treatments), and 20 normal subjects. Conjunctival cells were collected and incubated with specific monoclonal antibodies directed against CCR4, CCR5, and HLA-DR, in order to measure, in a masked manner using flow cytometry, the percentage of cells positive to each marker in the conjunctival epithelium.
Results: Compared to normal subjects, HLA DR expression was significantly elevated in glaucomatous patients, with a tendency toward higher levels in the multitreatment group and lower levels in patients treated with prostaglandins, which did not differ significantly from control values. Both CCR4 and CCR5 significantly increased in glaucoma patients on multitreatment or monotherapy compared with normal subjects.
Conclusion: This study demonstrates the overexpression of these two chemokine receptors in the conjunctival epithelium of patients treated for more than 1 year. Our results showing the simultaneous overexpression of CCR4 and CCR5 thus suggest that the chronic use of topical treatments may concurrently stimulate the TH1 and TH2 systems. These results evoke inflammatory mechanisms, combining allergy and toxicity, and confirm the complexity of inflammatory reactions occurring in the ocular surface of glaucoma patients.