Background/Purpose:  

Individuals with primary Sjogren’s syndrome (SS) may lack systemic autoantibodies. When defined by the absence of anti-SSA and –SSB antibodies, the reported range is 26-67%(J Autoimmun 2012;39:15). We sought to: 1) determine the prevalence of seronegativity, defined more broadly by the absence of antibodies to SSA fine specificities (Ro52 and Ro60, assayed individually) and to other relevant antigens, including cyclic citrullinated peptide (CCP), centromere (CENT), and rheumatoid factor (RF) and 2) compare these antibody profiles with non-SS controls.

Methods:  

We studied 149 consecutively enrolled SICCA registrants who had SS, defined by focal lymphocytic sialadenitis with a focus score ≥1 (FLS) and ocular surface staining score (OSS) ≥3, irrespective of serologic test results. Control subjects were 50 consecutive registrants lacking FLS, OSS ≥3, or whole unstimulated sialometry ≤0.1 ml/min. Subjects with known rheumatoid arthritis (RA) or systemic lupus (SLE) were eligible for SICCA, while those with systemic sclerosis (SSc) were excluded. Antibodies were assayed by ELISA (Ro52, SSB, and CCP), immunoprecipitation using in vitro transcription/translated protein (Ro60), or immunofluorescent staining (CENT).

Results:  

137 subjects had 1° and 12 had 2° SS (4 SLE, 8 RA). In 1°SS, anti-SSA and/or SSB were detected in 102 (74%, [66,82 CI]), including 32 with only anti-SSA and 2 with only anti-SSB; anti-CCP in 7 (5%); and anti-CENT in 8 (6%). The 50 control subjects included 1 with anti-SSA and -SSB, 4 with anti-SSB without -SSA, 6 with anti-CCP, and 1 with anti-CENT. One or more of these specificities were present in 109 (80%) of 1°SS and in 10 (20%) of control subjects. Of the 8 1°SS subjects with anti-CENT, 3 (38%) were judged to have limited SSc, and 4 (50%) had anti-SSA and/or -SSB. Inclusion of [ANA≥1:320 + RF] increased the autoantibody prevalence among 1°SS to 122 (82%), but not among the control subjects.

Conclusion:  

The prevalence of anti-SSA and –SSB seronegativity in this 1° SS sample was substantially less than in other cohorts. Anti-CCP and -CENT were present in an additional 6% of these seronegative patients, indicating the importance of other autoantibodies in the definition of 1° SS autoimmune subsets, particularly those with SSc overlap. The combination of ANA≥1:320 and RF, an alternative ACR classification criterion, only identified 2 (1.3%) additional 1°SS patients and thus has limited SS diagnostic utility. The 8-14% prevalence of anti-SSB, anti-CCP, RF, and ANA≥1:320 in the control population limited the diagnostic specificity of these autoantibodies.

Supported by NIH/NIDCR contract N01 DE32636 and NIAMS P30 AR053503

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/prevalence-of-seronegative-sjogrens-syndrome-a-comparative-study-from-the-sjogrens-international-collaborative-clinical-alliance-sicca-cohort/