Seronegative patients with primary Sjögren's syndrome and non-pSS sicca test positive for anti-SSA/Ro52 and -Ro60 in saliva.

Objectives: Testing for anti-SSA/Ro antibodies in serum is essential in the diagnostic work-up for primary Sjögren's syndrome (pSS). In this study, we aimed to validate our previous assay for detection of salivary anti-SSA/Ro52, and to develop assays for detection of salivary anti-SSA/Ro60 and for detection of anti-Ro52 and -Ro60 in plasma using the electric field-induced release and measurement (EFIRM) platform.
Methods: Whole saliva samples from two independent Danish cohorts (DN1 and DN2) including 49 patients with pSS, 73 patients with sicca symptoms, but not fulfilling the classification criteria for pSS (non-pSS sicca), and 51 healthy controls (HC), as well as plasma samples from the DN1 cohort were analyzed using EFIRM to detect anti-SSA/Ro52 and -Ro60.
Results: In the DN1 cohort, 100 % in the pSS group and 16 % in the non-pSS sicca group were serum anti-SSA/Ro positive by ELISA. EFIRM detected anti-SSA (Ro52 and/or -Ro60) in plasma and saliva in 100 % and 96 % patients with pSS, and 16 % and 29 % with non-pSS sicca. In the DN2 cohort, 80 % patients with pSS and 26 % with non-pSS sicca were serum anti-SSA/Ro positive. Salivary anti-SSA discriminated patients with pSS from HC and non-pSS sicca with an AUC range of 0.74-0.96 in the DN1 and DN2 cohorts. EFIRM discriminated pSS from non-pSS sicca with an AUC of 0.98 in plasma.
Conclusion: Our findings suggest that salivary anti-SSA/Ro antibodies are potential discriminatory biomarkers for pSS, which may also identify seronegative patients, addressing the unmet clinical need of early detection and stratification of pSS.
Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: David T.W. Wong reports financial support was provided by National Institute of Dental and Craniofacial Research. David T.W. Wong reports financial support was provided by Sjogrens Syndrome Foundation. David T.W. Wong reports a relationship with GlaxoSmithKline that includes:. David T.W. Wong reports a relationship with Mars Wrigley Confectionery Ltd. that includes:. David T.W. Wong reports a relationship with Colgate Palmolive that includes:. David T.W. Wong reports a relationship with Liquid Diagnostics that includes:. Sarah Kamounah, Fang Wei, Anne Marie Lynge Pedersen, David Wong, David Chia, Yeong Wook Wong has patent pending to University of California Los Angeles, University of Copenhagen and Seoul National University. D.T.W.W. is consultant for GlaxoSmithKline, Mars Wrigley, and Colgate-Palmolive and has ownership in Liquid Diagnostics LLC. No other disclosures relevant to this article were reported. Other authors declare no conflicts of interest. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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