Background/Purpose: Previous studies have demonstrated that years before clinical onset of auto-immune diseases, auto-antibodies can already be present. However, it is also known that some individuals can have these auto-antibodies and will never develop an auto-immune disease. So far, little information is available on the presence of antibodies to extractable nuclear antigens (anti-ENA) in the general population in relation to the risk of developing an auto-immune disease, with special interest for Systemic Lupus Erythematosus (SLE) and primary Sjögren Syndrome (pSS).

Objectives To estimate the prevalence of anti-ENA and their association with the presence of known risk factors for SLE and pSS in the general Dutch population.

Methods: Methods Lifelines is a prospective population-based cohort study in the Netherlands. Cross-sectional data from 40,135 participants were analyzed. The detection of anti-ENA was performed using the ENA-CTD (connective tissue disease) screen on the Phadia-250 analyzer with a ratio >1.0 considered positive. An extensive questionnaire was taken on demographic and clinical information (e.g. early musculoskeletal symptoms). Furthermore, some general blood parameters were available. SLE and pSS were defined by a combination of self-reported SLE or pSS, specific medication use and visiting a medical specialist within the last year. Characteristics were compared between 3 groups: SLE/pSS patients, anti-ENA positive, and anti-ENA negative participants.

Results: Results Of the total 40,135 consecutive individuals, 41 were detected as having defined SLE or pSS of whom 49% were anti-ENA positive. SLE/pSS patients were older and more often female. Of the remaining individuals (40,094), 1089 (2.7%) were found anti-ENA positive. Anti-ENA positivity was significantly associated with older age, female gender and joint stiffness compared to anti-ENA-negative participants. Interestingly, levels of haemoglobin, leucocytes and lymphocytes were significantly decreased in anti-ENA-positive participants compared to anti-ENA-negative participants. SLE/pSS participants had even significantly lower haemoglobin and reported even more joint stiffness then anti-ENA positive individuals. Lower lymphocyte levels, gender and older age appear as significantly independent predictors of anti-ENA positivity and also for being defined SLE/pSS. Of the anti-ENA positive individuals, 2.3% were positive for anti-dsDNA as well as anti-SSA. These individuals showed significantly lower lymphocyte-, leukocyte-, neutrophilic granulocyte- and monocyte levels compared to other anti-ENA positive participants.

Conclusion: Conclusion In this large population-based study, the prevalence of anti-ENA-positivity was 2.8% for the total group and 2.7% when excluding patients with SLE or pSS. Older age, female gender, joint complaints and lower levels of hemoglobin, leucocytes and lymphocytes were more frequently present in anti-ENA-positive participants. Longitudinal studies are performed up to 15 years to investigate which individuals might develop SLE or pSS to be able to develop prediction models.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-presence-of-extractable-nuclear-antigens-ena-antibodies-in-a-large-population-based-cohort-from-the-netherlands-and-their-association-with-known-risk-factors-for-systemic-lupus-erythematosus-and/