RESUMEN
INTRODUCTION: Systemic implications create a critical need for identification of dry eye patients with Sjögren syndrome (SS). Herein, we aimed to determine expressions of type I-III interferons (IFNs) in dry eye patients with or without underlying SS and their differential diagnosis. METHODS: A prospective, observational, case-control study was performed on 140 dry eye patients among which 78 patients were diagnosed with SS. Clinical evaluations included ELISA detections of serum type I IFN (IFN-α and IFN-ß, type II IFN (IFN-γ), and type III IFN (IFN-λ1/IL-29, IFN-λ2/IL-28, and IFN-λ3/IL-28B), as well as reporter cell assay for serum type I IFN activity. RESULTS: The serum levels of IFN-α and IFN-ß were notably higher in dry eye patients with SS than those without underlying SS (p < 0.0001). The functional assay for serum type I IFN activity showed the mean summed scores in dry eye patients with SS were remarkably increased compared to those without underlying SS (p < 0.0001). The serum levels of IFN-γ and IFN-λ1/IL-29 seemed higher in dry eye patients with SS than those without underlying SS (p < 0.0001). The serum levels of type I IFN (IFN-α combined with IFN-ß), type II IFN (IFN-γ level), and type III IFN (IFN-λ1/IL-29) used as a test to predict underlying SS among dry eye patients produced an area under the curve of 0.86, 0.73, and 0.94, respectively. CONCLUSION: Serum levels of type I-III IFNs, especially IFN-α, IFN-ß, and IFN-λ1/IL-29, may serve as a useful biomarker for identification of SS dry eye from non-SS dry eye.