The choice of anti-LEDGF/DFS70 assay matters: a comparative study of six assays

Alexander Troelnikov; Lauren Hender; Susan Lester; Thomas Paul Gordon; Tiffany Hughes; Dimitra Beroukas

doi:10.1016/j.pathol.2022.07.010

The choice of anti-LEDGF/DFS70 assay matters: a comparative study of six assays

Pathology. 2022 Dec;54(7):910-916. doi: 10.1016/j.pathol.2022.07.010. Epub 2022 Sep 14.

Authors

Alexander Troelnikov¹, Lauren Hender², Susan Lester³, Thomas Paul Gordon⁴, Tiffany Hughes⁵, Dimitra Beroukas⁴

Affiliations

¹ Department of Immunopathology, SA Pathology, Adelaide, SA, Australia; Department of Allergy and Clinical Immunology, Flinders Medical Centre, Bedford Park, SA, Australia; Flinders University, Bedford Park, SA, Australia. Electronic address: alexander.troelnikov@sa.gov.au.
² Department of Immunopathology, SA Pathology, Adelaide, SA, Australia.
³ Rheumatology Unit, The Basil Hetzel Institute, Woodville, SA, Australia.
⁴ Department of Immunopathology, SA Pathology, Adelaide, SA, Australia; Flinders University, Bedford Park, SA, Australia.
⁵ Department of Allergy and Clinical Immunology, Flinders Medical Centre, Bedford Park, SA, Australia; Flinders University, Bedford Park, SA, Australia.

PMID: 36241554
DOI: 10.1016/j.pathol.2022.07.010

Abstract

Lens-epithelial derived growth factor (LEDGF/DFS70) autoantibodies result in the commonly observed dense fine speckled (DFS) pattern by anti-nuclear antibody (ANA) assay. However, there is no consensus approach for confirmation of this autoantibody specificity. To evaluate current approaches, we examined inter-assay agreement between six anti-LEDGF/DFS70 assays. A total of 395 consecutive sera samples from routine ANA diagnostics were obtained, tested by routine ANA, anti-ENA line immunoblot assay (LIA) and anti-dsDNA assay and with six anti-DFS/LEDGF assays: the EuroLine-LIA (Euro-LIA), Medical and Biological Laboratories ELISA (MBL-ELISA), Phadia-EliA (EliA), QUANTA Flash CLIA, EuroImmun ELISA (Euro-ELISA) and Immco-Diagnostics HEp-2 ELITE/DFS-Knockout (HEp-2KO). Of 395 sera, 108 tested positive by at least one assay. Despite general good concordance between all assays across the cohort (Gwet's AC1=0.89), within the target DFS-ANA pattern group inter-assay agreement was poor (AC1=0.59). Euro-LIA, CLIA and MBL-ELISA assays were most concordant, but CLIA and Euro-LIA were also most likely to identify discordant positive results. EliA and Euro-ELISA had poorer agreement, which could be attributable to ill-matched cut-offs between assays. HEp-2KO was frequently discordant with all other assays tested. Euro-LIA, CLIA and MBL-ELISA were most concordant at manufacturer's specifications and are suited for use in clinical laboratories. Modified assay thresholds are required to ensure comparative results for Euro-ELISA and EliA. HEp-2KO assay is frequently discordant with all other assays, making it less suited for routine diagnostics. The study highlights the importance of considering inter-assay variability when developing a diagnostic strategy for anti-LEDGF/DFS70 autoantibodies in clinical laboratories.

Keywords: ANA; DFS dense fine speckled; ELISA; Hep 2; LEDGF lens epithelial derived growth factor; antinuclear antibody; autoantibody; chemiluminscent assay; line immunoassay.

MeSH terms

Adaptor Proteins, Signal Transducing / metabolism
Antibodies, Antinuclear
Autoantibodies
Autoimmune Diseases* / diagnosis
Fluorescent Antibody Technique, Indirect / methods
Humans
Intercellular Signaling Peptides and Proteins / metabolism
Transcription Factors / metabolism

Substances

Adaptor Proteins, Signal Transducing
Transcription Factors
Antibodies, Antinuclear
Autoantibodies
Intercellular Signaling Peptides and Proteins