Investigating the Relationship between Serum Interleukin-17 Levels and Systemic Immune-Mediated Disease in Patients with Dry Eye Syndrome

PURPOSE: To investigate the association between dry eye syndrome (DE) and serum levels of interleukin (IL)-17 in patients with systemic immune-mediated diseases. METHODS: IL-17 and IL-23 levels were measured in the sera of patients whose tear production was <5 mm on the Schirmer test. Subjects included patients with chronic graft-versus-host disease (GVHD), rheumatoid arthritis (RA), Sjogren's syndrome (SS), systemic lupus erythematosus (SLE), and no systemic disease. Corneal/conjunctival fluorescein staining was scored and the correlation between the score and the IL-17 level was evaluated. RESULTS: A strong correlation existed between IL-17 level and the type of systemic disease. IL-17 was significantly elevated in patients with chronic GVHD compared to those with RA and SS. IL-17 was not detectable in patients with SLE or in those without systemic disease. IL-23 was not detected in any of the subjects. IL-17 was significantly increased in patients with high fluorescein staining scores. CONCLUSIONS: Our data suggest that IL-17 is involved in the pathogenesis of DE in patients with systemic immune-mediated diseases.