Objectives: Testing for anti-SSA/Ro antibodies in serum is essential in the diagnostic work-up for primary
Sjogren ¨ ’s syndrome (pSS). In this study, we aimed to validate our previous assay for detection of salivary antiSSA/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 antiSSA/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.