Abstract
BACKGROUND: Sjögren's syndrome (SjS) is a relatively common autoimmune disease characterized by oral and ocular dryness. There is an increasing need for simple, sensitive and rapid technologies for the diagnosis of SjS and other autoimmune diseases. Here we investigated whether a quick version of luciferase immunoprecipitation systems (QLIPS) could be used to produce a rapid, specific and quantitative test to detect autoantibodies associated with SjS. METHODS: Using QLIPS, which requires only ten minutes of incubation, a cohort of control and SjS sera were tested for antibodies to three SjS autoantigens (La, Ro60 and Ro52). Sensitivity and specificity of the QLIPS tests were compared with LIPS and existing ELISA data. The QLIPS test for Ro52 was then evaluated with a new validation cohort and its diagnostic performance determined. RESULTS: Using QLIPS, autoantibodies to three SjS antigens, La, Ro60, and Ro52 were detected in 49%, 56% and 70%, respectively, of the SjS patients and none of the controls (100% specificity). With antibody titers in the Ro52-seropositive SjS samples approximately 1,000 times higher than the healthy controls, not only was Ro52 the most informative, but detection of anti-Ro52 antibodies under these non-equilibrium conditions was improved compared to the standard 2 hour LIPS format. Validation of the anti-Ro52 QLIPS test in a new, independent cohort of SjS and control serum samples showed 66% sensitivity and 100% specificity. CONCLUSION: Together these results suggest that the QLIPS format for Ro52 yields both a more rapid and more discriminating test for detecting Ro52 autoantibodies than existing immunoassays and has the potential to be adapted for point-of-care evaluation of patients with SjS and other rheumatologic diseases.