Anti-DFS70 antibodies: an update on our current understanding and their clinical usefulness

Reflecting on a decade of the international consensus on ANA patterns (ICAP): Accomplishments and challenges from the perspective of the 7th ICAP workshop

The International Consensus on ANA Patterns (ICAP) is an ongoing international initiative dedicated to harmonizing technical and interpretation aspects of the HEp-2 IFA test. Comprised of internationally recognized experts in autoimmunity and HEp-2 IFA testing, ICAP has operated for the last 10 years by promoting accurate reading, interpretation, and reporting of HEp-2 IFA images by professionals involved in various areas related to autoimmune diseases, such as clinical diagnostic laboratories, academic research, IVD industry, and patient care. ICAP operates through continuous information exchange with the international community and encourages the participation of younger experts from all over the world. The 7th ICAP workshop has addressed several aspects that originated from this interaction with the international community and has effectively established objective goals and tasks to be delivered over the next two years. Some of these are outlined in this article, including the planning of three audio-visual educational modules to be posted at the www.anapattern.org website, the classification of two novel HEp-2 IFA patterns, the implementation of a project dedicated to continuously updating the information on the clinical and immunologic relevance of the HEp-2 IFA patterns, and the launch of two additional branches of the HEp-2 Clinical and Immunological (HEp-2 CIC) project.

High serum prevalence of autoreactive IgG antibodies against peripheral nerve structures in patients with neurological post-COVID-19 vaccination syndrome

Background

Patients suffering from neurological symptoms after COVID-19 vaccination (post-COVID-19 vaccination syndrome (PCVS)) have imposed an increasing challenge on medical practice, as diagnostic precision and therapeutic options are lacking. Underlying autoimmune dysfunctions, including autoantibodies, have been discussed in neurological disorders after SARS-CoV-2 infection and vaccination. Here, we describe the frequency and targets of autoantibodies against peripheral nervous system tissues in PCVS.

Methods

Sera from 50 PCVS patients with peripheral neurological symptoms after COVID-19 vaccination and 35 vaccinated healthy controls were used in this study. IgG autoreactivity was measured via indirect immunofluorescence assays on mouse sciatic nerve teased fibers. The frequencies of autoantibodies were compared between groups using Fisher's exact test. Serum anti-ganglioside antibodies were measured in ganglioside blots. Autoantibody target identification was performed using immunoprecipitation coupled to mass spectrometry. Subsequent target confirmation was conducted via cell-based assays and ELISA.

Results

Compared with controls, PCVS patients had a significantly greater frequency of autoantibodies against peripheral nervous system structures (9/50(18%) vs 1/35(3%); p=0.04). Autoantibodies bound to paranodes (n=5), axons (n=4), Schmidt-Lanterman incisures (n=2) and Schwann cell nuclei (n=1). Conversely, antibodies against gangliosides were absent in PCVS patients. Target identification and subsequent confirmation revealed various subunits of neurofilaments as well as DFS-70 as autoantibody epitopes.

Conclusion

Our data suggest that autoantibodies against nervous system tissue could be relevant in PCVS patients. Autoantibodies against neurofilaments and cell nuclei with so far non-established links to this disease spectrum should be further elucidated to determine their biomarker potential.

Complex patterns on HEp-2 indirect immunofluorescence assay in a large sample referred for anti-cell autoantibodies detection

Introduction

The combination of patterns is a frequent and challenging situation in the daily laboratory routine of autoantibodies testing using HEp-2 cells indirect immunofluorescence assay (HEp-2-IFA). Recently, the Brazilian Consensus on Autoantibodies (BCA) named these combinations as complex patterns (CPs) and organized them into 3 subtypes: multiple, mixed, and composite. This study aimed to describe the most frequent combinations of HEp-2-IIF patterns according to this new nomenclature.

Methods

Routine HEp-2-IFA results reported in January and June 2017 were reviewed using the new BCA classification. Visual pattern recognition was performed by experts on HEp-2-IFA readings, using the International Consensus on Antinuclear Antibodies (ANA) Patterns (ICAP) and BCA recommendations.

Results

54,990 serum samples from different patients were tested for ANA-HEp-2, and 11,478 (20.9%) were positive at a titer ≥ 1/80. Among these positive samples, 1,111 (9.7%) displayed CPs, divided into 95 different combinations. A higher proportion of CPs was observed in the pediatric age group. Multiple, mixed, and composite patterns were present in 85.3, 5.4, and 9.5% of the samples, respectively. In the multiple/mixed pattern group (n=1,005), double, triple, and quadruple combinations (ICAP/BCA codes) were observed in 97.7%, 2.2%, and 0.1%, respectively. The double nuclear pattern was the most prevalent combination observed (67.6%). The most common CPs registered were AC-4 (nuclear fine speckled) + AC-6,7 (nuclear discrete dots) (n=264); AC-2 (nuclear dense fine speckled) + AC-6,7 (n=201); AC-4+AC-8,9,10 (nucleolar) (n=129); and AC-3 (centromere)+AC-4 (n=124). All of these combinations were in the multiple subgroup.

Conclusion

Almost 10% of positive results in the HEp-2 procedure displayed CPs. Among the 3 subtypes of CPs proposed, the multiple pattern was the most prevalent, especially in the pediatric population. The AC-4, AC-2, and AC-6,7 were the most prevalent single patterns observed in the combinations described in this study. There was a significant association between age and the prevalence of most combined patterns. The AC-4+AC-6,7 combination was the most prevalent complex pattern detected regardless of the age group. The AC-2+AC-6,7 was more prevalent in younger individuals. The concepts involved in the CPs definition should add value to the reading and interpretation of the HEp-2-IIF assay.

A novel magnetic bead-based immunoprecipitation method for anti-dense fine speckled 70 antibodies

The indirect immunofluorescence assay (IIFA) on HEp-2 cells has been widely used for screening anti-nuclear antibodies (ANA) that are associated with systemic autoimmune rheumatic diseases (SARD). Sera containing ANA display multiple distinct fluorescence patterns on HEp-2 cells. Among them, a dense fine speckled (DFS) pattern caused by anti-DFS70 antibodies has been reported to have higher prevalence in healthy individuals than in patients with SARD. This DFS pattern is often difficult to distinguish amongst other SARD-associated ANA patterns, in particular a mixed homogeneous and speckled pattern. Furthermore, a strong DFS pattern can mask other SARD-associated patterns. Hence, we developed a novel immunoprecipitation method using magnetic beads to remove anti-DFS70 antibodies in serum prior to running IIFA. We also aimed to confirm the presence of anti-DFS70 and to uncover any SARD-associated ANA patterns masked by a strong DFS pattern. The sera used in our study were from 70 individuals who had routine ANA screen, of which 35 sera had an isolated DFS pattern with monospecific anti-DFS70 antibodies confirmed by a complementary assay, and 35 were control sera without a DFS pattern. An immunoprecipitation method using magnetic beads coated with recombinant human full length DFS70 protein was developed. The performance of this new method was evaluated in comparison to an immunoadsorption method using the same DFS70 protein. Our newly developed immunoprecipitation method demonstrated excellent sensitivity (91.4%) and specificity (100%) in confirming the DFS pattern associated with anti-DFS70 in sera. Additionally, our method was able to remove anti-DFS70 and uncover SARD-associated ANA patterns masked by a strong DFS pattern. It also showed a clearer background on IIFA than that of the immunoadsorption method. The novel magnetic bead-based immunoprecipitation method demonstrated satisfactory performance in removing anti-DFS70 without interfering with the detection of other antibodies. It can be easily integrated with IIFA to confirm anti-DFS70 associated DFS pattern. Additionally, it can simultaneously unmask other ANA patterns, which cannot be achieved by a conventional protocol that requires a complementary anti-DFS70 specific assay to be performed. Therefore, the novel method provides a more effective and accurate solution for ANA screening.

Dense fine speckled nuclear immunofluorescence: A mildly reassuring antinuclear antibody pattern meriting consideration

INTRODUCTION

Antinuclear antibodies (ANAs) are regarded as a hallmark of connective tissue diseases (CTDs) and play a key role in their diagnosis, but the value of some particular antibodies in management of patients and the disease prognosis is controversial. The mechanism underlying the production of ANAs in CTDs, other chronic inflammatory conditions and even in healthy people, is not completely elucidated. Anti-DFS70 antibodies connected with the dense fine speckled autoantigen of 70 kD, known as the lens epithelium-derived growth factor p75, are a subgroup of ANAs. Their presence and coexistence with other antibodies and their clinical significance are the matter of debate.

METHODS

Based on literature data, the authors focused on current knowledge explaining the role of anti-DFS70 antibodies in selected CTDs.

RESULTS

However, the literature data is ambiguous and does not fully support the validity of the anti-DFS70 assay for a specific CTD diagnosis. Most researchers claim that the presence of anti-DFS70 as the only one usually exclude the diagnosis of CTD. Nevertheless, its coexistence with other ANAs is not an excluding factor but has predictive value due to more favorable course of CTD. Such situations may also suggest an enhanced risk of the development of a CTD in the future.

CONCLUSIONS

Although more studies are needed in this field, it seems reasonable to ascertain the presence of anti-DFS70 in routine clinical practice.

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.

Postacute Sequelae of SARS-CoV-2: Musculoskeletal Conditions and Pain

Musculoskeletal and pain sequelae of COVID-19 are common in both the acute infection and patients experiencing longer term symptoms associated with recovery, known as postacute sequelae of COVID-19 (PASC). Patients with PASC may experience multiple manifestations of pain and other concurrent symptoms that complicate their experience of pain. In this review, the authors explore what is currently known about PASC-related pain and its pathophysiology as well as strategies for diagnosis and management.

The Nuclear Dense Fine Speckled (DFS) Immunofluorescence Pattern: Not All Roads Lead to DFS70/LEDGFp75

The monospecific dense fine speckled (DFS) immunofluorescence assay (IFA) pattern is considered a potential marker to aid in exclusion of antinuclear antibody (ANA)-associated rheumatic diseases (AARD). This pattern is typically produced by autoantibodies against transcription co-activator DFS70/LEDGFp75, which are frequently found in healthy individuals and patients with miscellaneous inflammatory conditions. In AARD patients, these antibodies usually co-exist with disease-associated ANAs. Previous studies reported the occurrence of monospecific autoantibodies that generate a DFS-like or pseudo-DFS IFA pattern but do not react with DFS70/LEDGFp75. We characterized this pattern using confocal microscopy and immunoblotting. The target antigen associated with this pattern partially co-localized with DFS70/LEDGFp75 and its interacting partners H3K36me2, an active chromatin marker, and MLL, a transcription factor, in HEp-2 cells, suggesting a role in transcription. Immunoblotting did not reveal a common protein band immunoreactive with antibodies producing the pseudo-DFS pattern, suggesting they may recognize diverse proteins or conformational epitopes. Given the subjectivity of the HEp-2 IFA test, the awareness of pseudo-DFS autoantibodies reinforces recommendations for confirmatory testing when reporting patient antibodies producing a putative DFS pattern in a clinical setting. Future studies should focus on defining the potential diagnostic utility of the pseudo-DFS pattern and its associated antigen(s).

Anti-DFS70 antibodies in systemic lupus erythematosus: Prevalence in a large Chinese cohort and an unexpected association with anti-dsDNA antibodies by a long-term follow-up

Objective

Monospecific autoantibodies to dense fine speckles 70 (DFS70) antigen are purported to aid in excluding systemic autoimmune rheumatic diseases (SARD) such as systemic lupus erythematosus (SLE). However, the non-isolated anti-DFS70 still has a certain prevalence in SLE patients, and the clinical significance remains unclear. We aimed to investigate the prevalence, clinical relevance, and value of long-term monitoring of anti-DFS70 antibodies in SLE patients.

Methods

Anti-DFS70 antibodies were measured by enzyme-linked immunosorbent assay (ELISA) in 851 SLE patients, 211 healthy individuals, and 194 patients with other SARD (except SLE). Demographic, serological, and clinical associations of anti-DFS70 antibodies were analyzed by a stepwise multivariable logistic regression model. The correlation of anti-DFS70 with anti-dsDNA, anti-C1q, and SLE Disease Activity Index 2000 (SLEDAI-2K) was analyzed. Sixty-one SLE patients with follow-up time ranging from 2 to 57 months were measured anti-DFS70 antibodies using both ELISA and line immunoassay. The dynamic variations of anti-DFS70 antibodies were evaluated with anti-dsDNA, anti-C1q, and SLEDAI-2K during the follow-up.

Results

The prevalence of anti-DFS70 was significantly higher in SLE (20.7% (176/851)) than in healthy individuals (9.5% (20/211), p = 0.0002) and other SARD (10.8% (21/194), p = 0.002). Multivariable analysis revealed that anti-DFS70-positive SLE patients were associated with younger age (odds ratio (OR) = 0.982; 95% confidence interval (CI) = 0.969, 0.995), higher frequencies of anti-dsDNA (OR 1.598; 95% CI 1.107, 2.306) and anti-PCNA (OR 6.101; 95% CI 2.534, 14.688), and higher levels of serum IgG (OR 1.097; 95% CI 1.067, 1.129) and were more likely to be accompanied by mucosal ulcers (OR 5.921; 95% CI 1.652, 21.215). The O.D. value of anti-DFS70 positively correlated with levels of anti-dsDNA (r = 0.183, p < 0.0001) and anti-C1q (r = 0.181, p < 0.0001), respectively, but not with SLEDAI-2K (p = 0.920). During the follow-up, 49 (42 negative and 7 positive) patients remained stable with anti-DFS70 levels. The other 12 patients experienced significant changes in anti-DFS70, and 83.3% (10/12) of them showed similar trends between anti-DFS70 and anti-dsDNA by evaluation of dynamic variations.

Conclusion

Anti-DFS70 antibodies seem to be prevalent in Chinese SLE patients. The positive association of anti-DFS70 with anti-dsDNA and consistent dynamic variation between anti-DFS70 and anti-dsDNA during the follow-up suggested a potential relationship between anti-DFS70 and anti-dsDNA in patients with SLE.

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.

The Prevalence and Clinical Relevance of the DFS Immunofluorescence Staining Pattern in a Large ANA-Positive Cohort

Background

Although the dense fine speckled (DFS) immunofluorescence staining pattern has been studied by various researchers in recent years, its clinical associations remain unspecified. Thus, we performed a retrospective study in a non-selective population to explore the prevalence of this enigmatic antinuclear antibody (ANA) pattern and to determine its possible clinical associations with any identifiable pathology.

Methods

We retrieved the results of ANA testing ordered by various departments in 2019 to study the prevalence of DFS pattern. Demographic characteristics and clinical features of these participants were also collected from the electronic medical record system. Correlation analysis was made to study its clinical associations and a p-value < 0.05 was considered statistically significant.

Results

The prevalence of ANA positivity was 37.4% among 72,204 serum samples of which the median age was 44 (interquartile range: 31, 56) years old and 68.0% were women. The prevalence of the DFS staining pattern was 1.1% in the total population and accounted for 3.1% in the ANA-positive population. There were 97.6% of these cases displaying the DFS pattern with a low titer of ANA (≤1:320; starting serum dilution: 1:100). We found that this pattern correlated with several pathological conditions, such as skin disorders (25.1%), alopecia (4.6%), and obstetric complications (6.6%).

Conclusion

The presence of the DFS immunofluorescence staining pattern may accompany several pathological conditions and may be a signal of localized inflammation within certain organs or tissues, especially the skin.

The temporal course of T- and B-cell responses to vaccination with BNT162b2 and mRNA-1273

OBJECTIVES

To investigate the response of the immune system (and its influencing factors) to vaccination with BNT162b2 or mRNA-1273.

METHODS

531 vaccinees, recruited from healthcare professionals, donated samples before, in between, and after the administration of the two doses of the vaccine. T- and B-cell responses were examined via interferon-γ (IFN-γ) release assay, and antibodies against different epitopes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (S1 and NCP) were detected via ELISA and surrogate neutralization assay. Results were correlated with influencing factors such as age, sex, prior infection, vaccine received (BNT162b2 or mRNA-1273), and immunosuppression. Furthermore, antinuclear antibodies (ANAs) were measured to screen for autoimmune responses following vaccination with an mRNA vaccine.

RESULTS

No markers of immunity against SARS-CoV-2 were found before the first vaccination. Two weeks after it, specific responses against SARS-CoV-2 were already measurable (median ± median absolute deviation (MAD): anti-S1 IgG 195.5 ± 172.7 BAU/mL; IgA 6.7 ± 4.9 OD; surrogate neutralization 39 ± 23.7%), and were significantly increased two weeks after the second dose (anti-S1 IgG 3744 ± 2571.4 BAU/mL; IgA 12 ± 0 OD; surrogate neutralization 100 ± 0%, IFN-γ 1897.2 ± 886.7 mIU/mL). Responses were stronger for younger participants (this difference decreasing after the second dose). Further influences were previous infection with SARS-CoV-2 (causing significantly stronger responses after the first dose compared to unexposed individuals (p ≤ 0.0001)) and the vaccine received (significantly stronger reactions for recipients of mRNA-1273 after both doses, p < 0.05-0.0001). Some forms of immunosuppression significantly impeded the immune response to the vaccination (with no observable immune response in three immunosuppressed participants). There was no significant induction of ANAs by the vaccination (no change in qualitative ANA results (p 0.2592) nor ANA titres (p 0.08) from pre-to post-vaccination.

CONCLUSIONS

Both vaccines elicit strong and specific immune responses against SARS-CoV-2 which become detectable one week (T-cell response) or two weeks (B-cell response) after the first dose.

A glimpse into the future of systemic lupus erythematosus

This viewpoint article on a forecast of clinically meaningful changes in the management of systemic lupus erythematosus (SLE) in the next 10 years is based on a review of the current state of the art. The groundwork has been laid by a robust series of classification criteria and treatment recommendations that have all been published since 2019. Building on this strong foundation, SLE management predictably will take significant steps forward. Assessment for lupus arthritis will presumably include musculoskeletal sonography. Large-scale polyomics studies are likely to unravel more of the central immune mechanisms of the disease. Biomarkers predictive of therapeutic success may enter the field; the type I interferon signature, as a companion for use of anifrolumab, an antibody against the common type I interferon receptor, is one serious candidate. Besides anifrolumab for nonrenal SLE and the new calcineurin inhibitor voclosporin in lupus nephritis, both of which are already approved in the United States and likely to become available in the European Union in 2022, several other approaches are in advanced clinical trials. These include advanced B cell depletion, inhibition of costimulation via CD40 and CD40 ligand (CD40L), and Janus kinase 1 (Jak1) and Tyrosine kinase 2 (Tyk2) inhibition. At the same time, essentially all of our conventional therapeutic armamentarium will continue to be used. The ability of patients to have successful SLE pregnancies, which has become much better in the last decades, should further improve, with approaches including tumor necrosis factor blockade and self-monitoring of fetal heart rates. While we hope that the COVID-19 pandemic will soon be controlled, it has highlighted the risk of severe viral infections in SLE, with increased risk tied to certain therapies. Although there are some data that a cure might be achievable, this likely will remain a challenge beyond 10 years from now.

Relationship Between Anti-DFS70 Autoantibodies and Oxidative Stress

BACKGROUND

The anti-DFS70 autoantibodies are one of the most commonly and widely described agent of unknown clinical significance, frequently detected in healthy individuals. It is not known whether the DFS70 autoantibodies are protective or pathogenic. One of the factors suspected of inducing the formation of anti-DFS70 antibodies is increased oxidative stress. We evaluated the coexistence of anti-DFS70 antibodies with selected markers of oxidative stress and investigated whether these antibodies could be considered as indirect markers of oxidative stress.

METHODS

The intensity of oxidative stress was measured in all samples via indices of free-radical damage to lipids and proteins such as total oxidant status (TOS), concentrations of lipid hydroperoxides (LPH), lipofuscin (LPS), and malondialdehyde (MDA). The parameters of the non-enzymatic antioxidant system, such as total antioxidant status (TAS) and uric acid concentration (UA), were also measured, as well as the activity of superoxide dismutase (SOD). Based on TOS and TAS values, the oxidative stress index (OSI) was calculated. All samples were also tested with indirect immunofluorescence assay (IFA) and 357 samples were selected for direct monospecific anti DFS70 enzyme-linked immunosorbent assay (ELISA) testing.

RESULTS

The anti-DFS70 antibodies were confirmed by ELISA test in 21.29% of samples. Compared with anti-DFS70 negative samples we observed 23% lower concentration of LPH (P = .038) and 11% lower concentration of UA (P = .005). TOS was 20% lower (P = .014). The activity of SOD was up to 5% higher (P = .037). The Pearson correlation showed weak negative correlation for LPH, UA, and TOS and a weak positive correlation for SOD activity.

CONCLUSION

In samples positive for the anti-DFS70 antibody a decreased level of oxidative stress was observed, especially in the case of samples with a high antibody titer. Anti-DFS70 antibodies can be considered as an indirect marker of reduced oxidative stress or a marker indicating the recent intensification of antioxidant processes.

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.

Low Prevalence of Anti-DFS70 Antibodies in Children With ANA-Associated Autoimmune Disease

INTRODUCTION

Anti-DFS70 antibodies occur in healthy individuals with various medical conditions. Unlike other anti-nuclear autoantibodies (ANA), they are not associated with systemic autoimmune disease in adult patients. To date, only a few studies have addressed the prevalence and/or clinical relevance of anti-DFS70 autoantibodies in children with and without autoimmune disease.

METHODS

Included in this retrospective cross-sectional mono-centric study were 308 pediatric patients with suspected or known autoimmune conditions who had a positive ANA in indirect immune fluorescence (IIF) screening and who were screened for anti-DFS70 antibodies by extractable nuclear antigen antibodies (ENA) immunoblot. Patients were assigned to four different diagnostic categories according to their diagnosis in the corresponding medical record: (a) absence of autoimmune or rheumatic disease (noARD, n = 116); (b) suspected autoimmunity without definitive diagnosis (sAI, n = 48); (c) other rheumatic disease (ORD) (n = 115); and (d) ANA-associated autoimmune disease (AARD, n = 29).

RESULTS

The prevalence of anti-DFS70 antibodies in the overall cohort was 33.8%. Among children without ARD (46.6%, 54/116), prevalence was significantly higher than among children with ORD (23.7%, 27/115, p = 0.0003) or AARD (17.2%, 5/29, p = 0.0054). Among all of the anti-DFS70 positive patients with AARD, other autoantibodies were found in the ENA immunoblot. In contrast, among anti-DFS70 positive patients with ORD (11.5%, 4/27), sAI (33.3%, 6/18) and noARD (16.7%, 9/54), other autoantibodies infrequently were detected (p = 0.0005). Patients with uveitis rarely were positive for anti-DFS70 antibodies (7.7%, 1/13). No association was found between anti-DFS70 antibodies and a history of allergic conditions (p = 0.51). The concordance between a typical DFS pattern in IIF and the detection of anti-DFS70 antibodies by immunoblot was 59.3%.

CONCLUSION

As with adults, the higher prevalence of anti-DFS70 among children without autoimmune disease confirms the mutual exclusion for this autoantibody in the pathogenesis of ARD. Among ANA-positive children, monospecific anti-DFS70 antibodies may help to discriminate between AARD and not-AARD-related conditions.

Antinuclear antibodies (ANA) as a criterion for classification and diagnosis of systemic autoimmune diseases

The classification and diagnosis of systemic autoimmune diseases are frequently based on a collection of criteria composed of clinical, laboratory, imaging, and pathology elements that are strongly associated with the respective disease. Autoantibodies are a distinctive hallmark and have a prominent position in the classification criteria of many autoimmune diseases. The indirect immunofluorescence assay on HEp-2 cells (HEp-2 IFA), historically known as the antinuclear antibody test, is a method capable of detecting a wide spectrum of autoantibodies. A positive HEp-2 IFA test is part of the classification criteria for systemic lupus erythematosus (SLE) and juvenile idiopathic arthritis (JIA), as well as the diagnostic criteria for autoimmune hepatitis (AIH) and primary biliary cholangitis (PBC). A positive HEp-2 IFA test can appear as different morphological patterns that are indicative of the most probable autoantibody specificities in the sample. Only some of the HEp-2 IFA patterns are associated with the specific autoantibodies relevant to SLE, JIA, AIH, and PBC, whereas some other patterns occur mainly in non-related conditions and even in apparently healthy individuals. This paper provides a critical review on the subject and proposes that the classification and diagnostic criteria for SLE, JIA, AIH, and PBC could be improved by a modification on the HEp-2 IFA (ANA) criterion in that the staining patterns accepted for each of these diseases should be restricted according to the respective relevant autoantibody specificities.

•

Autoantibodies play a prominent role in the classification or diagnostic criteria of many autoimmune diseases.

•

ANA test is part of the classification criteria for SLE and JIA, as well as the diagnostic criteria for AIH.

•

Different HEp-2 IFA patterns indicate different autoantibodies and only some are associated with a specific disease.

•

ANA classification/diagnostic criteria should reflect the HEp-2 IFA patterns associated to the relevant autoantibodies.

Autoantibodies to dense-fine-speckled 70 (DFS70) do not necessarily rule out connective tissue diseases

OBJECTIVES

In some patients with antinuclear antibodies (ANA), a pattern called anti-dense-fine-speckled-70 antibody (anti-DFS70) can be detected. Presence of anti-DFS70 is less frequently observed in patients with connective tissue diseases (CTD) and is therefore used as an exclusion criterion by some rheumatologists. To date, however, it is unclear as to what extent the presence of an anti-DFS70 can reliably rule out CTDs.

METHODS

Data of 460 patients who were tested for the presence of anti-DFS70 at University Hospital Bonn, Germany, were analyzed. Patients were examined with regard to clinical symptoms and signs, type of disease, type of CTD, fulfillment of the classification criteria, presence of anti-DFS70, other systemic autoantibodies and ANA titers by indirect immunofluorescence (IIF) assays and line immunoassays. Differences in DFS70 antibody status between patients with CTD were examined. In addition, specificity, sensitivity, and positive predictive values for different ANA titers were calculated.

RESULTS

In 182 of the 460 patients (of whom 79.8% were female), CTD was diagnosed. 354 patients (77.0%) tested negative, 81 (17.6%) positive and 25 (5.4%) borderline for anti-DFS70. Twenty-one patients (25.9%) with a positive result had CTD. No significant differences were observed between anti-DFS70 positive and anti-DFS70 negative patients with CTD concerning age, gender, symptoms, clinical signs, and other disease-specific antibodies. However, of these 21 patients, only one patient showed the monospecific appearance of anti-DFS70. Anti-DFS70 had a sensitivity and a specificity of 26.9% and 86.8%, respectively, with a positive predictive value of 68.2% at an ANA titer of ≥1:160 with respect to the absence of CTD.

CONCLUSIONS

Autoantibodies to DFS70 seem to be prevalent in CTD patients and are thus not a good exclusion criterion. The monospecific occurrence of anti-DFS70 can, however, be helpful in ambiguous situations.

Dense fine speckled immunofluorescence pattern in a Chinese population: Prevalence and clinical association

OBJECTIVE

To provide information on the prevalence and possible clinical association in a Chinese population for medical practice of the dense fine speckled pattern (DFS pattern).

METHODS

A retrospective study was conducted with patients who had the DFS pattern from June 2018 to December 2019 in West China Hospital.

RESULTS

A total of 469 patients (1.27% of patients with positive anti-nuclear antibody indirect immunofluorescence (ANA IIF) test results) revealed the DFS pattern, of which 92.96% had isolated DFS pattern and 23.67% had titers above/equal to 1:320. The average age of patients with the DFS pattern was 43.45 years, and females accounted for 76.97% of them. Ten different kinds of diseases made up the vast majority of the disease spectrum, in which inflammatory or infectious diseases (46.11%), mental diseases (21.45%), and systemic autoimmune rheumatic diseases (SARDs) (18.23%) ranked in the top three. The most common SARDs were rheumatoid arthritis (RA), undifferentiated connective tissue disease (UCTD), and systemic lupus erythematosus (SLE). Forty-six patients (10.55%) had positive or suspicious extractable nuclear antigen (ENA) antibodies test results and a higher risk of suffering from SARDs. Forty-seven patients would be missed if the DFS pattern with negative ENA antibodies test result was considered as exclusion criterion of SARDs.

CONCLUSIONS

The DFS pattern is basically isolated and with low titer. It is unwise to exclude the diagnosis of SARDs only depending on the appearance of the DFS pattern. Autoimmune diseases-related antibodies, clinical information of patients, and long-term follow-up are of great importance to avoid missed or delayed diagnosis of SARDs.

Strong Association of the Myriad Discrete Speckled Nuclear Pattern With Anti-SS-A/Ro60 Antibodies: Consensus Experience of Four International Expert Centers

Introduction

The morphological patterns in indirect immunofluorescence assay on HEp-2 cells (HEp-2 IFA) reflect the autoantibodies in the sample. The International Consensus on ANA Patterns (ICAP) classifies 30 relevant patterns (AC-0 to AC-29). AC-4 (fine speckled nuclear pattern) is associated to anti-SS-A/Ro, anti-SS-B/La, and several autoantibodies. Anti-SS-A/Ro samples may contain antibodies to Ro60 and Ro52. A variation of AC-4 (herein designated AC-4a), characterized by myriad discrete nuclear speckles, was reported to be associated with anti-SS-A/Ro. The plain fine speckled pattern (herein designated AC-4b) seldom was associated with anti-SS-A/Ro. This study reports the experience of four expert laboratories on AC-4a and AC-4b.

Methods

Anti-Ro60 monoclonal antibody A7 was used to investigate the HEp-2 IFA pattern. Records containing concomitant HEp-2 IFA and SS-A/Ro tests from Durand Laboratory, Argentina (n = 383) and Fleury Laboratory, Brazil (n = 144,471) were analyzed for associations between HEp-2 IFA patterns and disease-associated autoantibodies (DAA): double-stranded DNA, Scl-70, nucleosome, SS-B/La, Sm, and U1-RNP. A total of 381 samples from Dresden Technical University (TU-Dresden), Germany, were assayed for HEp-2 IFA and DAA.

Results

Monoclonal A7 recognized Ro60 in Western blot and immunoprecipitation, and yielded the AC-4a pattern on HEp-2 IFA. Analyses from Durand Laboratory and Fleury Laboratory yielded compatible results: AC-4a was less frequent (8.9% and 2.7%, respectively) than AC-4b (26.1% and 24.2%) in HEp-2 IFA-positive samples. Reactivity to SS-A/Ro occurred in 67.6% and 96.3% of AC-4a-pattern samples against 23% and 6.8% of AC-4b pattern samples. Reciprocally, AC-4a occurred in 24% and 47.1% of anti-SS-A/Ro-positive samples, and in 3.8% and 0.1% of anti-SS-A/Ro-negative samples. Data from TU-Dresden show that the AC-4a pattern occurred in 69% of 169 anti-SS-A/Ro-monospecific samples (62% of all anti-SS-A/Ro-positive samples) and in 4% of anti-SS-A/Ro-negative samples, whereas anti-SS-A/Ro occurred in 98.3% of AC-4a samples and in 47.9% of AC-4b samples. In all laboratories, coexistence of anti-SS-B/La, but not other DAA, in anti-SS-A/Ro-positive samples did not disturb the AC-4a pattern. AC-4a was predominantly associated with anti-Ro60 antibodies.

Conclusions

This study confirms the association of AC-4a pattern and anti-SS-A/Ro in opposition to the AC-4b pattern. The results of four international expert laboratories support the worldwide applicability of these AC-4 pattern variants and their incorporation into ICAP classification under codes AC-4a and AC-4b, respectively. The AC-4 pattern should be maintained as an umbrella pattern for cases in which one cannot discriminate AC-4a and AC-4b patterns. The acknowledgment of the AC-4a pattern should add value to HEp-2 IFA interpretation.

The LEDGF/p75 Integrase Binding Domain Interactome Contributes to the Survival, Clonogenicity, and Tumorsphere Formation of Docetaxel-Resistant Prostate Cancer Cells

Patients with prostate cancer (PCa) receiving docetaxel chemotherapy invariably develop chemoresistance. The transcription co-activator lens epithelium-derived growth factor p75 (LEDGF/p75), also known as DFS70 and PSIP1, is upregulated in several human cancers, including PCa and promotes resistance to docetaxel and other drugs. The C-terminal region of LEDGF/p75 contains an integrase binding domain (IBD) that tethers nuclear proteins, including the HIV-1 integrase and transcription factors, to active chromatin to promote viral integration and transcription of cellular survival genes. Here, we investigated the contribution of the LEDGF/p75 IBD interactome to PCa chemoresistance. Quantitative immunoblotting revealed that LEDGF/p75 and its IBD-interacting partners are endogenously upregulated in docetaxel-resistant PCa cell lines compared to docetaxel-sensitive parental cells. Using specific human autoantibodies, we co-immunoprecipitated LEDGF/p75 with its endogenous IBD-interacting partners JPO2, menin, MLL, IWS1, ASK1, and PogZ, as well as transcription factors c-MYC and HRP2, in docetaxel-resistant cells, and confirmed their nuclear co-localization by confocal microscopy. Depletion of LEDGF/p75 and selected interacting partners robustly decreased the survival, clonogenicity, and tumorsphere formation capacity of docetaxel-resistant cells. These results implicate the LEDGF/p75 IBD interactome in PCa chemoresistance and could lead to novel therapeutic strategies targeting this protein complex for the treatment of docetaxel-resistant tumors.

How to report the antinuclear antibodies (anti-cell antibodies) test on HEp-2 cells: guidelines from the ICAP initiative

Results of the anti-nuclear antibodies-indirect immunofluorescence assay (anti-cell antibodies test) on HEp-2 cell substrates should be communicated to clinicians in a standardized way, adding value to laboratory findings and helping with critical clinical decisions. This paper proposes a test report based on the practices informed by 118 laboratories in 68 countries, with recommendations from the International Consensus on ANA Patterns (ICAP) group. Major focus is placed on the report format containing endpoint titers, immunofluorescence patterns together with anti-cell (AC) nomenclature, remarks on follow-up or reflex testing, and possible other autoantibody associations. ISO 15,189 directives were integrated into the test report. Special situations addressed include serum screening dilutions and endpoint titers, relevance of immunofluorescence patterns with special attention to cytoplasmic patterns, mixed and compound patterns, and how to report different titers corresponding to multiple patterns or autoantibodies in the same sample. This paper suggests a subtitle for the HEp-2-IIFA, namely anti-cell antibodies test, which could gradually substitute the original outdated ANA nomenclature. This ICAP pro forma report represents a further step in harmonizing the way relevant clinical information could be provided by laboratories.

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.

Properties of Uncommon Indirect Immunofluorescence Staining Patterns Determined during Antinuclear Antibody Detection on HEp-2 Cells

In this study, we aimed to assess the prevalence of uncommon staining patterns found during testing for the presence of antinuclear antibodies (ANA) and to determine their association with certain antibodies and clinical diagnoses. Presence of ANA and the staining pattern was determined in 10955 samples using indirect immunofluorescence (IIF) on HEp-2 cells. ANA-positive samples were assessed for presence of 14 specific antibody types using a microbead based system. Demographic data (age, sex) and clinical diagnoses were collected from the referral documentation. Particular staining patterns were then compared with a representative comparison group comprised of samples with common staining patterns using these criteria. There were 22 patterns present in less than 3% of samples each and these were jointly present in 42.43% of ANA-positive samples. Specific antibodies were found in proportions similar to the comparison group (46.06%) and varied significantly between patterns. Likewise, there were significant differences in antibody distribution in particular patterns. Some patterns were associated with presence of rheumatic diseases or inflammatory arthropathies, while in others there was a concurrent diagnosis of liver disease, or a neoplastic process. Many of the uncommon IIF patterns have distinctive characteristics that warrant further investigation in order to determine their role in diagnosing various diseases, not limited only to the illnesses of the rheumatic spectrum. IIF on HEp-2 cells remains an irreplaceable method because of the diversity of ANA, only a number of which can be detected using other standardised methods.

Systemic Lupus Erythematosus Classification and Diagnosis

Since the European League Against Rheumatism/American College of Rheumatology 2019 classification criteria for systemic lupus erythematosus (SLE) were published, they were externally validated by groups worldwide. In particular, the new criteria worked well also in East Asian and pediatric cohorts. Antinuclear antibodies (ANA) as an entry criterion were critically discussed, but the group of ANA-negative patients is small (<5%) worldwide. Specificity of the criteria is dependent on correct attribution only of those criteria that are not better explained by other causes. Although the classification criteria should not be used for diagnosis, many novel aspects inform diagnostic considerations.

Prevalence of anti-dense fine speckled 70 antibodies in healthy individuals and patients with antinuclear antibody-associated autoimmune rheumatic diseases in Japan

Previous studies from various countries have reported anti-dense fine speckled pattern (DFS)70 antibody prevalence but few studies have been from Asia. We investigated the prevalence of anti-DFS70 autoantibodies in a Japanese cohort of healthy individuals (HI) and patients with antinuclear antibody-associated autoimmune rheumatic diseases (AARD).Enzyme-linked immunosorbent assay and indirect immunofluorescence were performed using samples from 250 HI and 276 AARD patients.The overall anti-DFS70 antibody prevalence in HI was 16.4%, with 12.8% for males and 20.0% for females (sex difference; P = .12). In AARD patients, the anti-DFS70 antibody prevalence in systemic lupus erythematosus, mixed connective tissue disease, systemic sclerosis, dermatomyositis and polymyositis (DM/PM), Sjögren syndrome, and rheumatoid arthritis (RA) was 22.1%, 14.3%, 14.3%, 3.0%, 21.3%, and 18.1%, respectively (no significant difference between AARD patients except DM/PM and HI). The prevalence of isolated anti-DFS70 antibody in HI and all AARD patients excluding RA was 14.8% (37/250) and 4.4% (9/204), respectively (P  < .01 vs HI). Among anti-DFS70 antibody-positive cases, 63.4% (26/41) were DFS pattern by IIF and 23.5% (8/34) were HI and AARD patients excluding RA, respectively.The anti-DFS70 antibody prevalence in HI and AARD patients in Japan was similar. Furthermore, the anti-DFS70 antibody prevalence in HI and AARD in Japan is higher than in HI and AARD in regions other than Asia. This makes AARD differential diagnosis by antinuclear antibody screening difficult.

Understanding and interpreting antinuclear antibody tests in systemic rheumatic diseases

Antinuclear antibodies (ANAs) are valuable laboratory markers to screen for and support the diagnosis of various rheumatic diseases (known as ANA-associated rheumatic diseases). The importance of ANA testing has been reinforced by the inclusion of ANA positivity as an entry criterion in the 2019 systemic lupus erythematosus classification criteria. In addition, specific ANAs (such as antibodies to Sm, double-stranded DNA (dsDNA), SSA/Ro60, U1RNP, topoisomerase I, centromere protein B (CENPB), RNA polymerase III and Jo1) are included in classification criteria for other rheumatic diseases. A number of techniques are available for detecting antibodies to a selection of clinically relevant antigens (such as indirect immunofluorescence and solid phase assays). In this Review, we discuss the advantages and limitations of these techniques, as well as the clinical relevance of the differences between the techniques, to provide guidance in understanding and interpreting ANA test results. Such understanding not only necessitates insight into the sensitivity and specificity of each assay, but also into the importance of the disease context and antibody level. We also highlight the value of titre-specific information (such as likelihood ratios).

Anti-DFS70 Antibodies Among Patient and Healthy Population Cohorts in China: Results From a Multicenter Training Program Showing Spontaneous Abortion and Pediatric Systemic Autoimmune Rheumatic Diseases Are Common in Anti-DFS70 Positive Patients

Objective

Anti-DFS70 antibodies correlating with the nuclear dense fine speckled (DFS) pattern in the HEp-2 indirect immunofluorescence assay (IFA) are less common in patients with systemic autoimmune rheumatic disease (SARD) than in healthy subjects and their clinical associations remain elusive. We hosted a multi-center HEp-2 IFA training program to improve the ability of clinical laboratories to recognize the DFS pattern and to investigate the prevalence and relevance of anti-DFS70 antibodies.

Methods

DFS pattern sera identified by HEp-2 IFA in 29 centers in China were redirected to a central laboratory for anti-DFS70 testing by line immunoblot assay (LIA), enzyme-linked immunosorbent assay (ELISA), and IFA with HEp-2 ELITE/DFS70-KO substrate. Anti-extractable nuclear antigen antibodies were measured by LIA and the clinical relevance was examined in adult and pediatric patients.

Results

HEp-2 IFA positive rate and DFS pattern in positive sera were 36.2% (34,417/95,131) and 1.7% (582/34,417) in the patient cohort, and 10.0% (423/4,234) and 7.8% (33/423) in a healthy population, respectively. Anti-DFS70 prevalence among sera presenting the DFS pattern was 96.0, 93.7, and 49.6% by ELISA, LIA, and HEp-2 ELITE, respectively. 15.5% (52/336) of adult and 50.0% (20/40) of pediatric anti-DFS70 positive patients were diagnosed with SARD. Diseases most common in anti-DFS70 positive patients were spontaneous abortion (28.0%) in adults and juvenile idiopathic arthritis (22.5%) in pediatric patients.

Conclusion

Accurate DFS pattern identification increased the detection rate of anti-DFS70 antibodies by ELISA and LIA. Anti-DFS70 antibodies are remarkably high in cases of spontaneous abortion and in pediatric SARD patients, but not prevalent in adult SARD patients.

Diagnosing Organic Causes of Schizophrenia Spectrum Disorders: Findings from a One-Year Cohort of the Freiburg Diagnostic Protocol in Psychosis (FDPP)

Introduction: Secondary schizophrenia spectrum disorders (SSDs) have clearly identifiable causes. The Department for Psychiatry and Psychotherapy at the University Hospital Freiburg has continued to expand its screening practices to clarify the organic causes of SSDs. This retrospective analysis was carried out to analyze whether a comprehensive organic diagnostic procedure could be informative in patients with SSDs. Methods and Participants: The “Freiburg Diagnostic Protocol in Psychosis” (FDPP) included basic laboratory analyses (e.g., thyroid hormones), metabolic markers, pathogens, vitamin status, different serological autoantibodies, rheumatic/immunological markers (e.g., complement factors), cerebrospinal fluid (CSF) basic and antineuronal antibody analyses, as well as cranial magnetic resonance imaging (cMRI) and electroencephalography (EEG). The findings of 76 consecutive patients with SSDs (55 with paranoid–hallucinatory; 14 with schizoaffective; 4 with hebephrenic; and 1 each with catatonic, acute polymorphic psychotic, and substance-induced psychotic syndromes) were analyzed. Results: Overall, vitamin and trace element deficiency was identified in 92%. Complement factor analyses detected reduced C3 levels in 11%. Immunological laboratory alterations were detected in 76%. CSF analysis revealed general alterations in 54% of the patients, mostly with signs of blood–brain barrier dysfunction. cMRI analyses showed chronic inflammatory lesions in 4%. Combination of EEG, cMRI, and CSF revealed alterations in 76% of the patients. In three patients, autoimmune psychosis was suspected (4%). Discussion: On the basis of these findings, we conclude that a comprehensive diagnostic procedure according to the FDPP in patients with SSD is worthwhile, considering the detection of secondary, organic forms of SSDs, as well as alterations in “modulating factors” of the disease course, such as vitamin deficiency. Larger studies using comprehensive diagnostic protocols are warranted to further validate this approach.

Anti-DFS70 antibodies detected by specific methods in patients with thrombosis or recurrent pregnancy loss: no evidence of an association

A dense fine speckled pattern (DFS) caused by antibodies to the DFS70 kDa nuclear protein is a relatively common finding while testing for anti-nuclear antibodies (ANA) by indirect immunofluorescence (IIF) on HEp-2 cells. However, despite many efforts and numerous studies, the clinical significance of anti-DFS70 antibodies is still unknown as they can be found in patients with various disorders and even in healthy subjects. In this study we aimed at verifying whether these antibodies are associated with thrombotic events or with unexplained recurrent pregnancy loss (RPL). We studied 443 patients with venous or arterial thrombosis or RPL and 244 controls by IIF on HEp-2 cells and by a DFS70-specific chemiluminescent immunoassay (CIA). The DFS pattern was observed in IIF in 31/443 (7.0%) patients and in 6/244 (2.5%) controls (p = 0.01) while anti-DFS70 specific antibodies were detected by CIA in 11 (2.5%) patients and in one (0.4%) control (p = 0.06). Positive samples, either by IIF or by CIA, were then assayed by a second DFS70-specific line-immunoassay (LIA) method: 83.3% of the CIA positive samples were confirmed DFS70 positive versus only 29.7% of the IIF positive samples. These findings show that IIF overestimates anti-DFS70 antibody frequency and that results obtained by specific CIA and LIA assays do not indicate that venous or arterial thrombosis or RPL are linked to a higher prevalence of anti-DFS70 antibodies.

Investigating associations between anti-nuclear antibody positivity and combined long-term exposures to NO2, O3, and PM2.5 using a Bayesian kernel machine regression approach

BACKGROUND

Air pollution has many adverse health effects, but the combined or synergistic effects of multiple ambient air pollutants on anti-nuclear antibodies (ANA, a serologic marker of systemic autoimmune rheumatic disease, SARDs) have never been assessed.

OBJECTIVE

To flexibly model ANA and individual and joint associations of long-term exposures to nitrogen dioxide (NO₂), ozone (O₃), and fine particles matter (PM_2.5) using a Bayesian Kernel machine regression (BKMR) approach and to compare the results to those from individual logistic regressions.

METHODS

Serum ANA positivity was determined for randomly selected CARTaGENE general population subjects in Quebec, Canada. CARTaGENE is a public research platform created for investigating the associations of environmental, genomic, and lifestyle factors on chronic diseases. Ambient NO₂, O₃, and PM_2.5 estimates, derived from ground-measurement and chemical-transport-model simulated concentrations, were assigned to subjects based on residential postal codes at the time of blood collection. Our models adjusted for age, sex, French Canadian origin, smoking, and family income.

RESULTS

Concentrations of NO₂, O₃, and PM_2.5 were closely correlated in space. In the 5485 CARTaGENE subjects studied, we did not see clear associations between NO₂, PM_2.5 or O₃ and ANA positivity, with either the BKMR or logistic models.

CONCLUSIONS

BKMR did not uncover associations between ANA positivity and individual levels or combined exposures of NO₂, O₃, and PM_2.5; neither did simpler logistic models. Additional studies (in younger populations, in distinct race/ethnicity groups, and/or in jurisdictions with high air pollution levels) would be helpful to reinforce current findings.

Twenty years of research on the DFS70/LEDGF autoantibody-autoantigen system: many lessons learned but still many questions

The discovery and initial characterization 20 years ago of antinuclear autoantibodies (ANAs) presenting a dense fine speckled (DFS) nuclear pattern with strong staining of mitotic chromosomes, detected by indirect immunofluorescence assay in HEp-2 cells (HEp-2 IIFA test), has transformed our view on ANAs. Traditionally, ANAs have been considered as reporters of abnormal immunological events associated with the onset and progression of systemic autoimmune rheumatic diseases (SARD), also called ANA-associated rheumatic diseases (AARD), as well as clinical biomarkers for the differential diagnosis of these diseases. However, based on our current knowledge, it is not apparent that autoantibodies presenting the DFS IIF pattern fall into these categories. These antibodies invariably target a chromatin-associated protein designated as dense fine speckled protein of 70 kD (DFS70), also known as lens epithelium-derived growth factor protein of 75 kD (LEDGF/p75) and PC4 and SFRS1 Interacting protein 1 (PSIP1). This multi-functional protein, hereafter referred to as DFS70/LEDGF, plays important roles in the formation of transcription complexes in active chromatin, transcriptional activation of specific genes, regulation of mRNA splicing, DNA repair, and cellular survival against stress. Due to its multiple functions, it has emerged as a key protein contributing to several human pathologies, including acquired immunodeficiency syndrome (AIDS), leukemia, cancer, ocular diseases, and Rett syndrome. Unlike other ANAs, "monospecific" anti-DFS70/LEDGF autoantibodies (only detectable ANA in serum) are not associated with SARD and have been detected in healthy individuals and some patients with non-SARD inflammatory conditions. These observations have led to the hypotheses that these antibodies could be considered as negative biomarkers of SARD and might even play a protective or beneficial role. In spite of 20 years of research on this autoantibody-autoantigen system, its biological and clinical significance still remains enigmatic. Here we review the current state of knowledge of this system, focusing on the lessons learned and posing emerging questions that await further scrutiny as we continue our quest to unravel its significance and potential clinical and therapeutic utility.

Pattern of antinuclear antibody and antiextractable nuclear antigen antibody test requisitions in Riyadh

Background:

International guidelines for screening of systemic autoimmune rheumatic diseases (SARD) recommend antinuclear antibody (ANA) test as the first level test and antiextractable antigen (anti-ENA) along with anti-double-stranded DNA (anti-dsDNA) as second line tests following a reactive ANA test. This study was performed to assess adherence to international guidelines for investigation of SARD and to compare the requesting pattern of ANA and second level tests between rheumatology and nonrheumatology physicians in Riyadh.

Methodology:

This retrospective cross-sectional study comprising of 300 first time requests for investigation of SARD was performed in the immunology unit at King Khalid University Hospital (KKUH). Data were collected between April and May 2018. Information regarding the requesting physicians’ specialty and the first time requested tests (ANA, anti-dsDNA, and anti-ENA) were extracted from the electronic medical records. Reasons for requisition of tests were also recorded.

Results:

Of the total requests, 159 (53%) requests included ANA as a single first level test, whereas the rest of the requests (n = 141, 47%) included ANA test in conjunction with second level tests for the investigation of SARD. From the department of rheumatology, 14 (29.8%) initial requests were for ANA test as the only first line investigation that was significantly lower than 145 (57.3%) similar requests from the rest of the departments (P < 0.001).

Conclusion:

ANA and second level tests requests by physicians particularly among rheumatologists lacked compliance to international guidelines. The current study strongly suggests the need for strict compliance to international guidelines for screening of systemic autoimmune disorders among physicians.

ANA as an entry criterion for the classification of SLE

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease with highly variable clinical and immunological manifestations. In the classification of patients with this condition, the presence of an antinuclear antibody (ANA) is an important element, with new criteria from the American College of Rheumatology and European League against Rheumatism positioning ANA positivity by an immunofluorescence assay on HEp2-cells (HEp2-IFA) or by an equivalent solid phase assay as the entry criterion. This positioning is based on assumptions about the frequency of ANA positivity in SLE as well as the reliability of the assays. Studies indicate that these assumptions are still a matter of uncertainty since both types of assay show considerable variability and patients with SLE may display negative results in ANA testing. These findings suggest caution in positioning ANA positivity as an entry criterion for classification and point to the value of alternative serological approaches for ANA determinations.

Autoantibodies in SLE: prediction and the p value matrix

Autoantibodies (AA) and antinuclear antibodies (ANA) serve as key diagnostic and classification criteria for systemic lupus erythematosus (SLE). More than 200 different AA have been reported in SLE, although only a handful (<20) are considered "mainstream" because they are widely and routinely used in diagnostic, research and clinical medicine. Although the vast majority of AA have been relegated to the diminished status of "orphan" AA, some serve as predictors of SLE because they first appear in very early or subclinical SLE. Some AA are pathogenic, whereas others are thought to protect against or ameliorate disease progression and, hence, taken together can be used as predictive biomarkers of prognosis. Although studies have shown that specific AA are detected in the preclinical phase of SLE and are biomarkers of increased risk of developing the disease, AA are currently not widely used to predict very early SLE in individuals who have low pretest probability of disease. With the advent of multianalyte arrays with analytic algorithms, emerging evidence indicates that when certain combinations of biomarkers, such as the interferon signature and stem cell factor accompany AA and ANA, the predictive power for SLE is markedly increased.

Investigation of anti-DFS70 antibody in patients with systemic autoimmune rheumatic diseases

INTRODUCTION

Dense fine-speckled 70 (DFS70) antibody is defined as an antinuclear antibody (ANA) pattern in indirect immunofluorescence (IIF). The presence of anti-DFS70 antibody has been shown as a potential marker for the exclusion of systemic autoimmune rheumatic diseases (SARD) (without any other SARD-associated autoantibodies). We aimed to investigate the frequency of anti-DFS70 antibodies in patients with SARD and in the blood bank donors (BD).

MATERIALS AND METHODS

The study group consists of 418 rheumatoid arthritis (RA), 101 systemic lupus erythematosus (SLE), 71 Sjogren's syndrome (SS), 43 ankylosing spondylitis (AS), 36 systemic sclerosis-scleroderma (SSc), 2555 undifferentiated connective tissue disease (UCTD), and 507 BD. All samples were tested on the HEp-2 IIF-ANA assay. Samples that showed DFS70 pattern in IIF were confirmed by a specific DFS70 antibody enzyme-linked immunosorbent assay (ELISA).

RESULTS

The DFS70 pattern was detected in 43 (1.33%) in SARD and four (0.78%) in BD. The anti-DFS70 antibody was detected in three (0.59%) in BD, six (1.43%) in RA, three (2.97%) in SLE, one (1.40%) in SS, and 25 (0.97%) in UCTD, however, it was not detected in AS and SSc by ELISA. There was no significant difference between BD and SARD (p = 0.28). Distinctly, the frequency of anti-DFS70 was significantly different for SLE in SARD (p = 0.02).

CONCLUSION

Anti-DFS70 antibody was more prevalent in the subsets of SARD than BD. This result may be related to the demographic formation of study groups and individual immunological status. More comprehensive studies are needed to investigate the importance of the anti-DFS70 antibody for SARD.Key Points• This study draws attention to the importance of anti-DFS70 antibodies in the diagnostic algorithm in systemic autoimmune rheumatic diseases.• This study emphasizes the further investigation of anti-DFS70 antibodies in undifferentiated connective tissue diseases.• This study emphasizes the need to verify the DFS70 pattern detected in IIF-ANA test for definitive diagnosis with additional confirmation methods.

Only monospecific anti-DFS70 antibodies aid in the exclusion of antinuclear antibody associated rheumatic diseases: an Italian experience

Background

The dense fine speckled (DFS) is one of the most common patterns that can be observed as a result of the anti-nuclear antibodies (ANA) test on HEp-2 cells and is mostly caused by antibodies to DFS70 as the main antigenic target. As was recently demonstrated, isolated anti-DFS70 positivity can be used as an aid in the exclusion of ANA associated rheumatic diseases (AARD) due to the opportunity to better interpret unexplained positive IIF ANA results.

Methods

Our study included 333 subjects with AARD, 51 undifferentiated connective tissue disease (UCTD) patients, 235 disease controls and 149 healthy blood donors from an Italian cohort. All samples were tested for anti-DFS70 and anti-ENA antibodies using QUANTA Flash assays (Inova Diagnostics, San Diego, CA, USA).

Results

No differences in the prevalence of anti-DFS70 antibodies were seen among AARD, non-AARD and UCTD (2.1% [7/333] vs. 2.3% [9/384] vs. 5.9% [3/51], respectively; p-value = 0.188). AARD patients positive for anti-DFS70 antibodies showed in all cases an accompanying anti-ENA specificity. In contrast, monospecific anti-DFS70 antibodies showed a significantly different distribution with a clear trend across the main groups (AARD vs. non-AARD vs. UCTD: 0% [0/7] vs. 22% [2/9] vs. 100% [3/3], p = 0.007). Anti-DFS70 antibody levels among AARD, non-AARD and UCTD patients were not significantly different (p = 0.094). Within the anti-DFS70 antibody positive cases, AARD cohort showed a higher variability (median [min–max]: 3.2 [3.2–450.8] CU) compared to non-AARD (median [min–max]: 3.2 [3.2–75.7] CU) and UCTD patients (median [min–max]: 3.2 [3.2–59.0] CU).

Conclusions

Our preliminary data showed a similar frequency of anti-DFS70 antibodies in AARD, UCTD and non-AARD cohorts. Monospecificity of anti-DFS70 antibodies but not their mere presence is the key element in the diagnostic algorithm. Mono-specific anti-DFS70 antibodies might be a helpful biomarker to discriminate individuals with AARD from non-AARD presenting with a positive ANA.