IL-21 plays an important role in primary Sjögren syndrome (SS) pathogenesis. The purpose of this study was to evaluate IL-21 expression in tears and the conjunctiva and to analyze the impact of IL-21 on primary SS dry eyes.
Eighty subjects were enrolled in this study: 30 patients with primary SS dry eye (30 eyes); 30 patients with non-SS dry eye (30 eyes), and 20 normal controls. Tear IL-21 levels were measured by flow cytometry, and IL-21 gene expression in the conjunctiva from impression cytology was evaluated by quantitative polymerase chain reaction. Ocular Surface Disease Index, tear film breakup time, Schirmer I test, and ocular surface staining scores were obtained for all patients.
Primary SS dry eyes had significantly higher tear IL-21 levels than non-SS dry eyes and normal controls (P < 0.01). In addition, IL-21 gene expression in the conjunctiva was also higher in primary SS dry eyes than in non-SS dry eyes and normal controls (P < 0.01). However, there were no significant differences in IL-21 expression in tears and the conjunctiva between non-SS dry eyes and controls. The tear IL-21 level was significantly correlated with ocular surface stain scores (r = 0.54, P < 0.01) and Schirmer I test values (r = −0.23, P < 0.05) in primary SS dry eyes.
Our findings suggest that severity of primary SS dry eye is associated with IL-21.
*Department of Ophthalmology and Visual Science, Seoul St Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea;
†Catholic Institute for Visual Science, College of Medicine, The Catholic University of Korea, Seoul, Korea;
‡Northfield Mount Hermon School, MA; and
§Division of Rheumatology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.
Reprints: So-Hyang Chung, MD, PhD, Department of Ophthalmology and Visual Science, College of Medicine, The Catholic University of Korea, Seoul St. Mary's Hospital, #505 Banpo-Dong, Seocho-Gu, Seoul 137-040, Korea (e-mail: firstname.lastname@example.org).
Supported by a grant of the Korea Health Technology R&D Project, Ministry of Health & Welfare, Republic of Korea (HI13C0016).
The authors have no conflicts of interest to disclose.
Received October 23, 2014
Received in revised form November 20, 2014
Accepted November 30, 2014