Longitudinal Tracking of Extractable Nuclear Antigen (ENA) Antibodies in a Quaternary Hospital Laboratory Cohort Reveals Dynamic Antibody Profiles

J Appl Lab Med. 2022 Jan 5;7(1):26-35. doi: 10.1093/jalm/jfab104.


Background: Antiextractable nuclear antigens (anti-ENAs) are regarded as diagnostic tests with no established value for serial monitoring. We therefore sought to establish the stability over time of anti-ENAs in a large diagnostic immunopathology laboratory.

Methods: A retrospective review of all patients who had a serial anti-ENA ordered at the Westmead Hospital (Sydney, Australia) was performed over 24 months. Anti-ENA characterization was performed using line immunoassay, and historical data were available from 2013 onward. The earliest available densitometry readings were compared with the latest available to examine for a change in quantitation or qualitative (serostatus) result (from negative to positive, and vice versa). Medical records were examined for clinical correlations.

Results: A total of 283 patients (24.1%) had serial testing of anti-ENA in the audit period, with each patient having an average of 3.9 ± 2.9 tests each. Most patients were diagnosed with systemic lupus erythematosus or primary Sjögren's syndrome. About 25% and 58% of patients had a qualitative and quantitative change, respectively, in at least 1 anti-ENA in the study period. Changes in anti-ENA levels correlated with erythrocyte sedimentation rate and disease activity. Increasing duration between serial tests increased the probability of observing a change in anti-ENA levels.

Conclusion: Certain anti-ENAs are dynamic autoantibodies that may have significance for monitoring disease activity. Laboratories may consider reporting quantitative results. Further disease- and autoantibody-specific studies are required to determine the clinical significance of changes in anti-ENAs.

Keywords: antinuclear antibodies; autoantibodies; autoimmunity; connective tissue disorders; extractable nuclear antigens.

MeSH terms

  • Antibodies, Antinuclear / analysis*
  • Humans
  • Laboratories, Hospital
  • Lupus Erythematosus, Systemic* / diagnosis
  • Retrospective Studies
  • Sjogren's Syndrome / diagnosis*


  • Antibodies, Antinuclear