Distribution of conjunctival HLA-DR expression and the pathogenesis of damage in early dry eyes

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.

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.

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.

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.