Distribution of Conjunctival HLA-DR Expression and the Pathogenesis of Damage in Early Dry Eyes

PURPOSE: To examine the expression of HLA-DR, a marker of inflammation, in the early stages of dry eye disease and to locate the appearance of this marker on specific areas of the bulbar conjunctiva. METHODS: Dry eye patients were identified and their condition classified as mild (n = 16) or moderate (n = 16) based on Schirmer testing, vital staining, tear break-up time, and symptom questionnaire scores. Brush cytology was used to collect epithelial cells from the nasal, temporal, and superior conjunctivae of patients and age-matched controls. HLA-DR positive cells were detected by immunohistochemical staining and quantified. RESULTS: Patients with moderate dry eye had the highest rate of conjunctival HLA-DR-positive cells, with significantly higher rates than controls regardless of which region of the conjunctiva was sampled (P < 0.01). The mild dry eye group had similar rates of HLA-DR-positive cells in the superior conjunctival region compared with controls. However, in the nasal and temporal regions, they displayed a significantly higher rate of HLA-DR-positive cells than controls (P < 0.01) and the nasal region showed a significant difference (P < 0.01) when compared with the temporal one. Some of these mild dry eyes had no vital staining. CONCLUSIONS: The HLA-DR expression pattern in mild and moderate dry eyes appears to reflect disease progression. Overexpression of HLA-DR in mild dry eyes showing no vital staining suggests that inflammation may be a primary cause of ocular surface damage. These data support the use of immunomodulatory drugs in the treatment of dry eye disease.