Monospecific anti-DFS70 antibodies are moderately helpful in excluding ANA-associated rheumatic disease in patients presenting with a dense fine speckled pattern – A systematic review and meta-analysis of diagnostic test accuracy

The significance of dense fine speckled pattern in antinuclear antibody-associated rheumatic disease and coexisting autoantibodies: A propensity score-matched cohort study

AIM

To investigate the relationship between the prevalence of antinuclear antibody (ANA) -associated rheumatic diseases (AARD) and the presence of dense fine speckled (DFS) and homogeneous patterns in ANA tests.

METHODS

This retrospective study enrolled adult patients with either a DFS or homogeneous pattern in their ANA test. A mixed pattern was defined as the presence of more than one pattern reported in the test. The presence of anti-DFS70 antibodies and other common autoantibodies were detected using EUROLINE ANA Profile 23. A 1:2 propensity score matching was applied to control for demographic and other interfering factors.

RESULTS

A total of 59 patients with a DFS pattern were enrolled and compared with a matched homogeneous group. The DFS group had a significantly lower prevalence of AARD (3.4% vs. 16.9%, p = .008) and the subgroup with anti-DFS70 antibodies showed an even lower prevalence (2% vs. 20%, p = .002). Among the 33 patients with monospecific anti-DFS70 antibodies, five had a mixed pattern, and all patients with common autoantibodies had an isolated DFS pattern.

CONCLUSIONS

The findings of this study suggest that patients with a DFS pattern in their ANA test may have a lower prevalence of AARD compared with those with a homogeneous pattern. However, an isolated DFS pattern in ANA testing does not necessarily indicate the presence of monospecific anti-DFS70 antibodies or AARD. Confirmatory testing for the monospecific anti-DFS70 antibody is mandatory to exclude AARD.

Detection of antinuclear antibodies: recommendations from EFLM, EASI and ICAP

OBJECTIVES

Antinuclear antibodies (ANA) are important for the diagnosis of various autoimmune diseases. ANA are usually detected by indirect immunofluorescence assay (IFA) using HEp-2 cells (HEp-2 IFA). There are many variables influencing HEp-2 IFA results, such as subjective visual reading, serum screening dilution, substrate manufacturing, microscope components and conjugate. Newer developments on ANA testing that offer novel features adopted by some clinical laboratories include automated computer-assisted diagnosis (CAD) systems and solid phase assays (SPA).

METHODS

A group of experts reviewed current literature and established recommendations on methodological aspects of ANA testing. This process was supported by a two round Delphi exercise. International expert groups that participated in this initiative included (i) the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) Working Group "Autoimmunity Testing"; (ii) the European Autoimmune Standardization Initiative (EASI); and (iii) the International Consensus on ANA Patterns (ICAP).

RESULTS

In total, 35 recommendations/statements related to (i) ANA testing and reporting by HEp-2 IFA; (ii) HEp-2 IFA methodological aspects including substrate/conjugate selection and the application of CAD systems; (iii) quality assurance; (iv) HEp-2 IFA validation/verification approaches and (v) SPA were formulated. Globally, 95% of all submitted scores in the final Delphi round were above 6 (moderately agree, agree or strongly agree) and 85% above 7 (agree and strongly agree), indicating strong international support for the proposed recommendations.

CONCLUSIONS

These recommendations are an important step to achieve high quality ANA testing.

Analysis of Ana/Dfs70 Pattern in a Large Cohort of Autoimmune/Autoinflammatory Diseases Compared with First Degree Relatives and Healthy Controls Evaluated from Colombia

Background: The presence of Antinuclear antibodies/Dense Fine Speckled 70 (ANA/DFS70) has been proposed as a negative biomarker in the process of exclusion of systemic autoimmune/autoinflammatory rheumatic diseases (SARD). The purpose was to evaluate and characterize ANA/DFS70 patients in a large Colombian population with SARD; rheumatoid arthritis (RA), Psoriasis (PsO), Undifferentiated connective tissue disease (UCTD), first-degree relatives of (FDR), and healthy controls (HC). Methods: ANA determination was performed using indirect immunofluorescence. Samples with positive dense fine granular staining in the nucleoplasm of the interphase cell (AC2) fluorescence were confirmed with CytoBead/ANA and ANA/modified (Knocked out for the PSPI1 gen). Results: 530 mestizo Colombian participants were included. ANA/DFS70 antibody positivity in the whole group was 2.3%, and 0.8% in SARD; no RA patients were positive. ANA/DFS70 positives in UCTD were three women; the average time of evolution of the disease was 9.4 years. The most frequent clinical findings were arthralgias, non-erosive arthritis, and Raynaud’s phenomenon. The PsO positive was a woman with C-reactive protein (CRP) positivity and a negative erythrocyte sedimentation rate (ESR) without any other positive autoantibody or extracutaneous manifestation. FDR and HC positives were 7/8 women. All were negative for other autoantibodies. Conclusions: ANA/DFS70 autoantibodies were present in Colombian patients with SARD at a shallow frequency, they were more prevalent in healthy individuals.

Anti-DFS70 Antibodies Are Associated With Proliferative Lupus Nephritis and Renal Pathological Activity

Objective

The significance of anti-dense fine speckles 70 (DFS70) antibodies in systemic lupus erythematosus (SLE) is still unclear, especially in lupus nephritis (LN) patients. We investigated the prevalence, clinical and pathological relevance of anti-DFS70 antibodies in LN patients.

Methods

Anti-DFS70 antibodies were measured using enzyme-linked immunosorbent assays in 377 biopsy-proven LN patients, 268 non-LN SLE patients, 232 chronic kidney disease (CKD) patients, and 78 healthy individuals (HI). Demographic, clinical, and pathological parameters were compared between LN patients with and without anti-DFS70 antibodies. Stepwise multivariable logistic regression was performed to identify covariates associated with anti-DFS70 antibodies.

Results

The prevalence of anti-DFS70 antibodies in LN (19.6%) was comparable to non-LN SLE patients (19.8%, P=0.9630), but was significantly higher than CKD patients (13.4%, P=0.0468) and HI (9.0%, P=0.0252). Using multivariable logistic regression analysis, the titer of anti-double-stranded DNA (dsDNA) antibodies (adjusted odds ratio=1.002, 95% confidence interval 1.001-1.003, P=0.004) was associated with positive anti-DFS70 antibodies in LN patients. In addition, anti-DFS70 antibodies were more prevalent in proliferative LN (22.0%, 68/309) compared to membrane LN patients (10.2%, 6/59, P=0.0376). Furthermore, LN patients with positive anti-DFS70 antibodies had significantly higher activity index (AI) compared to patients who were negative (8.0 vs 6.0, P=0.0131). However, the chronicity index was similar between the groups (3.0 vs 3.0, P=0.8412).

Conclusion

Anti-DFS70 antibodies were not associated with LN development in SLE patients but were associated with anti-dsDNA antibodies, proliferative LN, and renal AI. This suggests their potential to serve as a non-histological biomarker for LN subclass and activity status.

Autoantibodies in Common Connective Tissue Diseases: A Primer for Laboratory Professionals

Background

Autoimmune connective tissue disorders are a significant health concern throughout the world with an estimated prevalence of 3% to 5%. They are associated with a variety of autoantibodies that play roles in their diagnosis, risk stratification, prognostication, and/or management. While some autoantibodies have been well-characterized for use in clinical laboratories, many more are in the research stage. Rapid transition from research to clinical practice, lack of clinical guidelines, and harmonization across a rapidly growing number of commercially available tests create numerous challenges to clinicians and laboratories.

Content

This article briefly discusses common connective tissue disorders and their association with well-known autoantibodies, describes current methods used in clinical laboratories, and outlines their advantages and limitations in the context of these diseases.

Summary

Understanding the role of specific autoantibodies and various methodologies for autoantibody testing are important for laboratory professionals who may be introducing/repatriating new tests, updating existing tests, or advising clinicians/patients about testing options/results. Collaboration between laboratory professional staff and clinicians, around the advantages and limitations of each methodology, is also important in their appropriate clinical utilization.

Anti-DFS70 Antibodies for Differentiating Systemic Autoimmune Rheumatic Disease in Patients with Positive ANA Tests: A Systematic Review and Meta-Analysis

Anti-DFS70 antibodies have been proposed as a marker to exclude systemic autoimmune rheumatic disease (SARD). We conducted this systematic diagnostic test accuracy review and meta-analysis to determine the performance of anti-DFS70 antibodies in patients with a positive anti-nuclear antibody (ANA) test result to exclude SARD. We searched PubMed, Embase, Web of Science, Scopus and the Cochrane Library up to 22 February 2021, and included studies examining the diagnostic accuracy of anti-DFS70 antibodies in patients with a positive ANA test result. The results were pooled using a hierarchical bivariate model and plotted in summary receiver operating characteristic curves. R software and Stata Statistical Software were used for the statistical analysis. Eight studies with 4168 patients were included. The summary sensitivity was 0.19 (95% confidence interval: 0.12–0.28) and the specificity was 0.93 (95% confidence interval: 0.88–0.96). The area under the curve was 0.69 (95% confidence interval: 0.64–0.72). The meta-regression analysis showed that targeting only ANA-associated rheumatic disease was associated with higher specificity. In addition, the studies with a non-SARD prevalence of <80% and using a chemiluminescence assay were associated with higher specificity. Anti-DFS70 antibodies have high specificity for the exclusion of SARD among patients presenting with a positive ANA test, but the sensitivity is low.

Infusion of anti-DFS70 antibodies prolonged survival of lupus-prone mice

BACKGROUND

Systemic-lupus-nephritis is a chronic autoimmune disease characterized by immune complex deposition and a flare of autoantibodies and leading to renal injury.

OBJECTIVES

To expose anti-Dense-Fine-Speckled-70 (DFS70)-antibodies to genetically-prone-lupus-mice.

METHODS

NZBXW/F1 female mice were monitored for the onset of glomerulonephritis by proteinuria upon infusion of anti-DFS70 (40 μg/mouse), commercial-human-IgG (cIgG) or phosphate-buffered-saline (PBS) as controls. The survival time was detected by mice death. Circulating anti-dsDNA were tested by ELISA. Proteinuria, was defined by a standard semi-quantitative-Bayer-Multistix-dipstick. Kidney histology was analyzed by periodic-acid-Schiff-PAS staining.

RESULTS

A significantly higher percentage of anti-DFS70-infused mice exhibited prolonged survival time as compared with cIgG and PBS-subjected mice (p < 0.022). One mouse out of 10 mice injected with anti-DFS70-antibodies died at week 36, whereas, 6 out of 10 mice subjected with PBS found dead at this time. Eighty percent of anti-DFS70 injected mice did not show severe glomerulonephritis by histology.

CONCLUSIONS

anti-DFS70 attenuated the progression of glomerulonephritis and prolonged the survival time. Circulating anti-DFS70-autoantibodies may confer a protective role against renal injury in murine-lupus-nephritis. Our data may propose a novel therapy approach for lupus patients.