A new study found that a targeted multiplex assay for extractable nuclear antigen (ENA) antibodies delivered diagnostic performance comparable to two widely used commercial immunoassay platforms, while using a familiar enzyme immunoassay workflow that may be easier for laboratories to adopt.
ENA antibody testing is a key step in diagnosing systemic autoimmune rheumatic diseases after an initial antinuclear antibody screen. However, many multiplex testing systems require specialized instruments and significant capital investment, limiting access in laboratories with fewer resources. The investigators evaluated a new multiplex assay designed to detect eight clinically relevant ENA antibodies using a standard 96-well plate format rather than dedicated high-end multiplex instrumentation.
In a study published in Journal of Immunological Methods, researchers compared the assay with two established laboratory methods using serum samples from patients with autoimmune diseases. Because there is no universally accepted reference standard for ENA testing, the study focused on agreement between platforms rather than diagnostic accuracy against a clinical gold standard.
Across the three platforms, agreement was strongest for several antibody targets, including Jo-1, Sm, and CENP-B, while lower agreement was seen for TRIM21/Ro52 and SSB. The authors noted that these differences are consistent with previously recognized variability between ENA assays, reflecting differences in antigen preparation and presentation rather than necessarily indicating poorer performance by any individual method.
Jamie Platt, CEO and Co-founder of Pictor Holdings, says, "This peer-reviewed study is an important milestone because it demonstrates strong agreement with established commercial platforms and gives researchers confidence that targeted proteomics can be both analytically robust and practical to implement. We believe targeted proteomics has the potential to expand the information available to pathologists while supporting the scalability, reproducibility, and workflow efficiency needed to advance autoimmune disease research and future clinical translation."
The study also found that the assay produced reproducible results within manufacturing lots and across different production batches, supporting its analytical consistency for routine laboratory use.
A multiplex assay that operates within a conventional enzyme-linked immunoassay workflow could allow laboratories already equipped for standard ELISA testing to add simultaneous ENA antibody detection without investing in dedicated multiplex analyzers. According to the authors, this approach could improve access to autoimmune serology, particularly in laboratories serving resource-constrained regions.
"For pathology laboratories, the challenge is no longer simply measuring biomarkers," says Platt. "It's generating high-quality, targeted protein data that can be integrated into routine laboratory workflows. Autoimmune diseases are often complex and heterogeneous, making accurate, scalable protein analysis increasingly important for both research and future clinical applications."
The authors also highlighted several limitations. Comparisons were made against existing commercial assays rather than patient outcomes or an independent clinical reference standard, and workflow, implementation, and cost-effectiveness were not formally evaluated. The study was sponsored by the assay developer and all authors reported financial relationships with the company.
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