Objective The expression of antinuclear antibodies (ANA) is considered almost constant in systemic lupus erythematosus (SLE), although recent experience has suggested that many subjects with SLE considered for clinical trials are ANA negative at screening. The objective of this study is to determine whether assay variation can influence ANA detection in patients with established SLE.
Methods Sera from 103 patients with established SLE were tested using three different immunofluorescence assays (IFA) for ANA determination. ANA determinations were also performed by an ELISA and bead-based multiplex assay.
Results With IFA kits, the frequency of ANA negativity varied from 5 to 23 of 103 samples (4.9%–22.3%). The ELISA and multiplex assays showed that 12 (11.7%) and 14 (13.6%) samples were negative, respectively. Samples positive in all assays differed from those with discordant assay results in the frequency of historical anti–double-stranded DNA positivity and low complement levels at the time of blood sampling.
Discussion These findings indicate that ANA negativity occurs in patients with established SLE although the frequency varies depending on the assay kit. Given the range of negativity with well-validated assays, these findings raise questions about whether ANA positivity should be employed to determine eligibility for clinical trials.
- systemic lupus erythematosus
- autoimmune diseases
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Handling editor Josef S Smolen
Contributors DSP, PEL and BHR designed the study. DMS performed the assays and prepared the data for publication. DSP, PEL and BHR reviewed and interpreted the data and wrote the manuscript.
Funding This work was supported by the Lupus Industry Council.
Competing interests None declared.
Patient consent Obtained.
Ethics approval This study was approved by The Ohio State University and Duke University Medical Center.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement Data will be available to interested investigators who can submit requests.