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Correction to: Evaluation of a novel particle-based multi-analyte technology for the detection of anti-fibrillarin antibodies


 Objective: Systemic sclerosis (SSc) is a heterogeneous autoimmune disease associated with several anti-nuclear antibodies (ANA), including those in the classification criteria [anti-centromere, anti-topoisomerase I (Scl-70), anti-RNA Pol III]. However, the presence of less common antibodies such as anti-fibrillarin (U3-RNP), that generate a clumpy nucleolar pattern by HEp-2 indirect immunofluorescence assay (IFA, ICAP AC-9), are considered disease specific and are with clinical subsets of SSc, therefore playing a role in diagnosis and prognosis. A specific and sensitive anti-fibrillarin assay would be an important addition to serological diagnosis and evaluation of SSc. The goal of this study was to evaluate a new particle-based multi-analyte technology (PMAT) for the measurement of anti-fibrillarin antibodies Methods: A total of 149 patient samples were collected including 47 samples from France (Lyon and Paris, n=32) and Italy (Careggi Hospital, Florence, n=15) selected based on AC-9 HEp-2 IFA staining (>1:640, clumpy nucleolar pattern) and 102 non-SSc controls [inflammatory bowel disease (IBD) n=20, Sjögren’s syndrome (SjS) n=20, infectious disease (ID) n=7, systemic lupus erythematosus (SLE) n=17, rheumatoid arthritis (RA) n=17, and healthy individuals (HI) n=21]. All samples were tested on the anti-fibrillarin PMAT assay (research use only, Inova Diagnostics, USA). Additionally, the 47 anti-fibrillarin positive samples were also tested on PMAT assays for detecting other autoantibodies in ANA-associated rheumatic diseases (AARD). Anti-fibrillarin antibody data performed by fluorescence enzyme immunoassay (FEIA, Thermo Fisher, Germany) was available for 34 samples. Results: The anti-fibrillarin PMAT assay was positive in 31/32 (96.9%, France) and 12/15 (80.0 %, Italy) of samples preselected based on the AC-9 IIF pattern. Collectively, the PMAT assay showed 91.5% [95% Confidence Interval (CI): 80.1-96.6%] sensitivity with 100.0% (95% CI: 96.4-100.0%) specificity in non-SSc controls. Strong agreement was found between PMAT and FEIA with 100.0% positive qualitative agreement (34/34) and quantitative agreement (Spearman’s rho=0.89, 95% CI:0.77.9-0.95%, p<0.0001). Although most anti-fibrillarin positive samples were mono-specific (69.8%), some expressed additional antibodies (namely Scl-70, centromere, dsDNA, Ro52, Ro60, SS-B, Ribo-P, DFS70, and EJ). Conclusion: The new PMAT assay had high level of agreement to FEIA for the detection of anti-fibrillarin antibodies. Further studies are warranted to investigate the clinical associations and performance of the new method in combination with other critical markers in the SSc panel.