Autoantibodies to Dense Fine Speckles in Pediatric Diseases and Controls

Clinical Significance of Antibodies to DFS70 in Immunoinflammatory Rheumatic Diseases

The relevance of the problem of immunoinflammatory rheumatic diseases (IIRD) for modern medicine is determined by their high prevalence in the population, the difficulty of early diagnosis, the rapid development of disability and poor life prognosis. Recent data on the significance of anti-DFS70 have opened up new possibilities for optimizing the step-by-step diagnosis of IIRD. The detection of these antibodies can help in the interpretation of a positive result for antinuclear antibodies (ANA) by indirect immunofluorescence assay on HEp-2 cells (IIFA-HEp-2) in the absence of autoantibodies specific for IIRD. Detection of anti-DFS70 in antinuclear factor (ANF) seropositive patients without clinical and/or serological markers characteristic of a certain disease from the IIRD group can be considered as a potential marker that excludes this group of diseases.

Reliability and reproducibility of antinuclear antibody testing in pediatric rheumatology practice

Antinuclear antibody (ANA) testing is common practice among health care practitioners when evaluating children and adolescents with non-specific symptoms including fatigue and aches and pains. When positive, ANA results often lead to referrals to pediatric rheumatologists as these antibodies may be key indicators for specific pediatric rheumatologic diagnoses. The reliability and reproducibility of ANA tests varies with assay techniques and validation and interpretation of results. In the following article, review of ANA testing in pediatrics is provided along with case examples that demonstrate the reliability and reproducibility of these results in specific scenarios common in the practice of pediatric rheumatology. Guidelines for more accurate utilization of ANA testing are presented with the aim to improve testing and interpretation by ordering clinicians.

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.

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.

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.

Assessing vitamin D levels in an anti-DFS70 positive population: New insights emerging

Background: Anti-dense fine speckled 70 (DFS70) autoantibodies have more often been described in apparently healthy individuals than in patients with systemic autoimmune rheumatic diseases (SARD). The aim of this study was to explore the link between anti-DFS70 autoantibodies and vitamin D (25(OH)D) levels in an Italian adult cohort.Methods: Serum samples from 34 (five males and 29 females) anti-DFS70 positive patients (index cases), 34 ANA-negative healthy controls, 34 ANA-positive anti-DFS70 negative SLE patients, both groups age- and gender-matched with the index cases, 23 ANA-positive anti-DFS70 negative healthy blood donors and six female SARD patients showing mixed DFS positive pattern were collected and tested for 25(OH)D levels. Relevant demographics and lifestyle practices, body mass index (BMI), comorbidities, and use of medication were recorded for patients and healthy controls.Results: Mean serum levels of 25(OH)D were significantly higher in anti-DFS70 positive subjects (mean ± SD: 22.1 ± 9.8 ng/ml) than in ANA-negative healthy controls (mean ± SD: 17.3 ± 6.7 ng/ml; p = .03), ANA-positive healthy controls (mean ± SD: 15.2 ± 6.8 ng/ml; p = .01), SLE patients (16.6 ± 11.0 ng/ml; p = .01) and in patients with SARD (15.0 ± 5.6 ng/ml; p = .01). No statistically relevant differences in BMI, clinical, or demographic parameters were found.Conclusions: Our findings showed higher levels of vitamin D in anti-DFS70 positive subjects than in the controls, which is compatible with the hypothesis of the "benign" nature of anti-DFS70 antibodies.

Autoantibodies in Morphea: An Update

Skin autoimmune conditions belong to a larger group of connective tissue diseases and primarily affect the skin, but might also involve underlying tissues, such as fat tissue, muscle, and bone. Autoimmune antibodies (autoantibodies) play a role in autoimmune skin diseases, such as localized scleroderma also termed morphea, and systemic scleroderma, also called systemic sclerosis (SSc). The detailed studies on the biological role of autoantibodies in autoimmune skin diseases are limited. This results in a few available tools for effective diagnosis and management of autoimmune skin diseases. This review aims to provide an update on the detection and most recent research on autoantibodies in morphea. Several recent studies have indicated the association of autoantibody profiles with disease subtypes, damage extent, and relapse potential, opening up exciting new possibilities for personalized disease management. We discuss the role of existing autoantibody tests in morphea management and the most recent studies on morphea pathogenesis. We also provide an update on novel autoantibody biomarkers for the diagnosis and study of morphea.

Clinical significance of anti-DFS70 antibody in antinuclear antibody-positive samples with a dense fine speckled pattern

Background

When the dense fine speckled (DFS) pattern-antinuclear antibodies (ANA) are detected in the indirect immunofluorescence (IIF) assay, the presence of anti-dense fine speckles 70 (DFS70) antibodies has been suggested to facilitate the exclusion of ANA-associated rheumatic diseases (AARD). We evaluated the potential use of anti-DFS70 antibodies for verifying AARD in patients with a positive ANA result of the DFS pattern.

Methods

A total of 5509 patients who were requested ANA testing were included. The DFS pattern was confirmed using two IIF assays. Semiquantitative DFS70 ELISA (Euroimmun, Germany) was examined in samples with the DFS pattern.

Results

Among 639 ANA-positive patients, 19.6% displayed the DFS pattern. And 17.6% of patients with the DFS pattern were diagnosed with AARD. The low titer of 1:80 was more prevalent in the non-AARD group than in the AARD group (64.1% vs. 4.5%, p < 0.0001). Anti-DFS70 antibodies were positive in 60.0% of patients with the DFS pattern. The frequency of anti-DFS70 positivity was higher in the non-rheumatic disease (NRD) group (74.2%) than in the other rheumatic disease group (43.2%, p = 0.003) and the AARD group (45.5%, p = 0.019).

Conclusions

The DFS pattern is present in both AARD and non-AARD cases. In the DFS pattern, a low titer of 1:80 and isolated anti-DFS70 antibodies without AARD-associated antibodies represent a low likelihood of AARD. The presence of anti-DFS70 antibodies cannot exclude AARD and should be analyzed in combination with AARD-associated antibodies in the diagnostic algorithm.

Prevalence and serological profile of anti-DFS70 positive subjects from a routine ANA cohort

Anti-Dense Fine Speckled 70 (DFS70) antibodies are a common finding in clinical laboratory referrals. High prevalence of DFS70 autoantibodies in healthy population and usual negative association with Antinuclear Antibody (ANA)-associated autoimmune rheumatic diseases (AARD) were reported. The aim of this study was to evaluate the prevalence of DFS70 autoantibodies and their association with other autoantibodies in the context of a routine ANA referral cohort. Consecutive sera submitted for ANA screening were analyzed for anti-DFS70 antibodies by indirect immunofluorescence (IIF) (n = 3175, 1030 men and 2145 women) then confirmed by immunoblotting. Anti-DFS70 positive samples were also assayed for a large spectrum of other circulating autoantibodies. The prevalence of anti-DFS70 antibodies was 1.7% in the whole population and 4.6% in the ANA-positive samples. Comparison between DFS70 IIF and immunoblotting showed an excellent correlation between the two methods. The prevalence of anti-DFS70 positive was significantly higher in females (2.1%, 45/2145) than in males (1.0%, 10/1030). Of note, no concomitant autoantibodies were found in the DFS70-positive male group compared with DFS70-positive females group that showed other serum autoantibodies in the 51% of cases. Anti-DFS70 reactivity in male population may represent an useful biomarker predicting the absence of other autoantibodies. On the contrary, the serological profile of DFS70-positive females required further investigations in order to define the presence of concomitant disease-marker autoantibodies.

The importance of detecting anti-DFS70 in routine clinical practice: comparison of different care settings

Background:

Screening for antinuclear antibodies by indirect immunofluorescence (ANA-IIF) is essential in the diagnostic workup of ANA-associated autoimmune rheumatic diseases (AARDs). However, also healthy individuals may test positive, making the interpretation challenging. Recent reports suggest that dense fine speckled 70 antibodies (anti-DFS70) may facilitate this challenge. Here, we investigate their clinical importance based on data from four Belgian laboratories (one primary, two secondary and one tertiary care).

Methods:

At least one specific DFS70 assay (DFS70 IgG ELISA or lineblot [Euroimmun, full length antigen] and/or DFS70 IgG CLIA [Inova Diagnostics, truncated antigen]) was performed on four consecutive cohorts of homogeneous-like ANA-IIF samples (n=697). Co-occurrence with AARD-specific ANA and clinical information were documented in the anti-DFS70-positive samples.

Results:

Using a combination of solid phase techniques, we found between 7.6% and 26% anti-DFS70 in the different cohorts. Focusing on anti-DFS70 CLIA-positive samples without co-occurrence of AARD-specific ANA, we observed a trend towards lower frequency in tertiary (8% [p=0.0786]) and secondary care (12% [p=0.1275] and 6% [p<0.001]) compared to primary care (21%). Moreover, in this specific subpopulation, AARD was less frequent (0%–50% compared to 6%–77% in the total anti-DFS70-positive group).

Conclusions:

Anti-DFS70 prevalence depends on the applied assay and care setting. Our data suggest that, for an ANA-IIF-positive patient, it is rather the absence of AARD-associated ANA and clinical symptoms that contribute to the exclusion of AARD than the presence of anti-DFS70. Nevertheless, isolated anti-DFS70 helps to clarify positive ANA-IIF results, especially if pretest probability for AARD is low.

Recognition and Relevance of Anti-DFS70 Autoantibodies in Routine Antinuclear Autoantibodies Testing at a Community Hospital

Antinuclear autoantibodies (ANA) displaying a dense fine speckled pattern (DFS, ICAP AC-2) on HEp-2 cells are frequently observed in clinical laboratory referrals, often associated with anti-DFS70 specificity. Anti-DFS70 positive patients rarely develop systemic autoimmune rheumatic disease (SARD), especially in the absence of clinical evidence or additional anti-extractable nuclear antigen (ENA) antibodies, prompting suggestions that an isolated DFS70-specific ENA may be an exclusionary finding for SARD. In this study, the frequency and diagnostic significance of anti-DFS70 autoantibodies was investigated in a community hospital cohort of patients undergoing routine ANA testing. ANA screening was performed by HEp-20-10-based indirect immunofluorescence, followed by ENA profiling using a multiparametric line immunoassay (LIA). Of 6,511 patient samples tested for ANA in 2016, the DFS pattern was identified in 1,758 (27.0%), 720 (41.0%) of which were anti-DFS70 positive by LIA. Of these, 526 (73.1%) revealed isolated anti-DFS70 reactivity, while 194 (26.9%) showed additional ENA specificities. Among 1,038 anti-DFS70 negative or borderline samples, 778 (75.0%) were ENA profile negative, while the remaining 260 (25.0%) showed a varied presence of other ENA specificities. Chart reviews of patients with an isolated anti-DFS70 ANA affirmed that ANA-related SARD is rare in the absence of clinical evidence or other ENA specificities, there being no case thus far identified. Rheumatoid arthritis patients occasionally had an isolated anti-DFS70 ANA and were positive for rheumatoid factor and anti-cyclic citrullinated peptide antibodies. In conclusion, the recognition of a DFS ANA pattern using a mitotic-rich HEp-2 substrate, followed by confirmation of anti-DFS70 specificity should be a routine ANA testing service. Use of an expanded ENA profile and clinical correlation is necessary to affirm the "isolation" of anti-DFS70 as the cause of an ANA. Recognition of isolated anti-DFS70 ANA enables reassurance of patients that SARD is unlikely, thus avoiding referral for more extensive testing. The presence of significant elevations of other ENAs may reflect SARD and warrants close clinical correlation and follow-up.

Simultaneous Distinction of Monospecific and Mixed DFS70 Patterns During ANA Screening with a Novel HEp-2 ELITE/DFS70 Knockout Substrate

Systemic autoimmune connective tissue disorders are characterized by circulating antinuclear antibodies (ANA). Although there are several technologies available for ANA screening, indirect immunofluorescence (IIF) using Human epithelial cells-2 (HEp-2) substrate remains the primary and recommended method because of its superior sensitivity. HEp-2 substrates can detect a multitude of patterns resulting from autoantibody binding to various protein and nucleic acid autoantigens distributed throughout the nucleus and cytoplasm of the cells. The great diversity of monospecific and mixed patterns resulting from positive reactions on HEp-2 substrate also complicate the interpretation and accuracy of reporting. One specific example which received utmost attention recently is the dense fine speckled 70 (DFS70) pattern resulting from autoantibodies that specifically bind to a protein called lens epithelium derived growth factor (LEDGF). Lack of clear association with a specific systemic autoimmune disease and high prevalence in healthy populations have made accurate interpretation of DFS70 pattern important. Accurate distinction of DFS70 pattern from disease-associated patterns using conventional HEp-2 substrate is challenging. Moreover, frequent co-occurrence of DFS70 pattern along with disease-associated patterns such as homogeneous, speckled, and mixed homogeneous-speckled patterns complicate the IIF interpretation. The goal of this paper is to demonstrate the utility of a novel engineered HEp-2 IIF substrate that retains all advantages of conventional HEp-2 substrate while simultaneously providing the ability to distinguish DFS70 pattern with high confidence in both monospecific and mixed ANA positive examples. The new substrate is further able to unmask disease-associated ANA patterns previously concealed by DFS70 pattern.

Uveitis in children

PURPOSE OF REVIEW

The review provides updates on novel risk markers for the development of pediatric inflammatory uveitis and a severe disease course, on treatment of refractory disease, and on the measurement of visual outcomes.

RECENT FINDINGS

There are several new genetic markers, biomarkers, and clinical factors that may influence a child's uveitis disease course. It is important to identify children at risk for poor visual outcomes and who are refractory to traditional therapy. Racial disparities have recently been reported. We describe agents of potential benefit. In addition, we discuss the importance of patient reported outcomes in this population.

SUMMARY

Uveitis can lead to vision-threatening complications. Timely and aggressive treatment of children identified to be at risk for a severe uveitis course may lead to improved outcomes.

The Clinical Relevance of Anti-DFS70 Autoantibodies

Despite all the progress in the establishment of specific autoantibody assays, screening for antinuclear antibodies (ANA) by indirect immunofluorescence on HEp-2 cells for quality-oriented laboratory diagnosis of ANA associated rheumatic diseases (AARD) remains indispensable but is not without limitations. Recent data on the relevance of the dense fine speckled (DFS) pattern and anti-DFS70 antibodies disclosed novel possibilities to optimize the serological stepwise diagnostics of AARD. The DFS pattern on HEp-2 cells is well differentiated from the classic "homogeneous" ANA pattern associated with dsDNA antibodies. This is the most frequent pattern in high titer ANA-positive healthy persons. The most characteristic ANA specificity associated with DFS pattern is the anti-DFS70 antibody (synonym LEDGF antibody). The prevalence of anti-DFS70 antibodies in AARD patients is significantly lower compared with the prevalence in ANA-positive healthy persons. There is a negative association between anti-DFS70 antibodies and AARD, especially if no concomitant AARD-specific autoantibodies are found. Isolated anti-DFS70 antibodies are detectable in less than 1 % of AARD but are detectable in 2-22 % of healthy persons. In the presence of an isolated anti-DFS70 antibody, the posttest probability for AARD is reduced significantly. The significance of anti-DFS70 antibodies as a criterion that helps to exclude AARD is also confirmed by follow-up studies on anti-DFS70 antibodies of positive, healthy individuals, who did not develop any AARD during a 4 year observation period. Consequently, anti-DFS70 antibodies are valuable novel biomarkers for better interpretation of positive ANA in cases of negative AARD-associated autoantibodies and should be integrated in modified test algorithms to avoid unnecessary referrals and examinations of ANA-positive persons.

Analysis of DFS70 pattern and impact on ANA screening using a novel HEp-2 ELITE/DFS70 knockout substrate

Indirect immunofluorescence (IIF) using human epithelial cell (HEp-2) substrate is a widely used and the recommended method for screening of antinuclear antibodies (ANA). Dense fine speckled (DFS70) pattern on HEp-2 has been widely reported in various healthy and disease groups. Interpretation of DFS70 pattern can be challenging on a conventional HEp-2 substrate due to its similarity to some of the disease associated patterns. The high prevalence of DFS70 autoantibodies in normal population, lack of association with a particular disease group and a general negative association with systemic and ANA associated autoimmune rheumatic diseases (SARD/AARD) necessitates the confirmation of DFS70 pattern. Results using available commercial assays for confirmation of DFS70 autoantibodies do not always agree with IIF screening results further complicating the lab work flow and ANA algorithms. In this review, we discuss the prevalence of DFS70 antibodies and factors affecting the performance of IIF and DFS70 specific confirmatory assays. Factors that contribute to disagreement between DFS70 suspicion by IIF and confirmatory assays will also be discussed. In addition, we also describe a novel IIF HEp-2 substrate, and its positive impact on DFS70 reporting and ANA screening-confirmation algorithm.

An Update on Treatment of Pediatric Chronic Non-Infectious Uveitis

There are no standardized treatment protocols for pediatric non-infectious uveitis. Topical corticosteroids are the typical first-line agent, although systemic corticosteroids are used in intermediate, posterior and panuveitic uveitis. Corticosteroids are not considered to be long-term therapy due to potential ocular and systemic side effects. In children with severe and/or refractory uveitis, timely management with higher dose disease-modifying antirheumatic drugs (DMARDs) and biologic agents is important. Increased doses earlier in the disease course may lead to improved disease control and better visual outcomes. In general, methotrexate is the usual first-line steroid-sparing agent and given as a subcutaneous weekly injection at >0.5 mg/kg/dose or 10-15 mg/m2 due to better bioavailability. Other DMARDs, for instance mycophenolate, azathioprine, and cyclosporine are less common treatments for pediatric uveitis. Anti-tumor necrosis factor-alpha agents, primarily infliximab and adalimumab are used as second line agents in children refractory to methotrexate, or as first-line treatment in those with severe complicated disease at presentation. Infliximab may be given at a minimum of 7.5 mg/kg/dose every 4 weeks after loading doses, up to 20 mg/kg/dose. Adalimumab may be given up to 20 or 40 mg weekly. In children who fail anti-tumor necrosis factor-alpha agents, develop anti-tumor necrosis factor-alpha antibodies, experience adverse effects, or have difficulty with tolerance, there is less data available regarding subsequent treatment. Promising results have been noted with tocilizumab infusions every 2-4 weeks, abatacept monthly infusions and rituximab.

The prevalence and determinants of anti-DFS70 autoantibodies in an international inception cohort of systemic lupus erythematosus patients

Autoantibodies to dense fine speckles 70 (DFS70) are purported to rule out the diagnosis of SLE when they occur in the absence of other SLE-related autoantibodies. This study is the first to report the prevalence of anti-DFS70 in an early, multinational inception SLE cohort and examine demographic, clinical, and autoantibody associations. Patients were enrolled in the Systemic Lupus International Collaborating Clinics (SLICC) inception cohort within 15 months of diagnosis. The association between anti-DFS70 and multiple parameters in 1137 patients was assessed using univariate and multivariate logistic regression. The frequency of anti-DFS70 was 7.1% (95% CI: 5.7–8.8%), while only 1.1% (95% CI: 0.6–1.9%) were monospecific for anti-DFS70. In multivariate analysis, patients with musculoskeletal activity (Odds Ratio (OR) 1.24 [95% CI: 1.10, 1.41]) or with anti-β2 glycoprotein 1 (OR 2.17 [95% CI: 1.22, 3.87]) were more likely and patients with anti-dsDNA (OR 0.53 [95% CI: 0.31, 0.92]) or anti-SSB/La (OR 0.25 [95% CI: 0.08, 0.81]) were less likely to have anti-DFS70. In this study, the prevalence of anti-DFS70 was higher than the range previously published for adult SLE (7.1 versus 0–2.8%) and was associated with musculoskeletal activity and anti-β2 glycoprotein 1 autoantibodies. However, ‘monospecific’ anti-DFS70 autoantibodies were rare (1.1%) and therefore may be helpful to discriminate between ANA-positive healthy individuals and SLE.

Antinuclear antibody prevalence in a general pediatric cohort from Mexico City: discordance between immunofluorescence and multiplex assays

OBJECTIVE

To characterize antinuclear antibody (ANA) prevalence according to distinct assay methodologies in a pediatric cohort from Mexico City, and to further examine associations with age and sex.

METHODS

Serum ANA were measured by indirect immunofluorescence assay (IFA) and multiplex immunoassay in 114 children aged 9-17 years. IFA was considered positive at a cutoff titer of ≥1:80. Agreement between assay methods was assessed by kappa statistic. Sensitivity, specificity, and 95% confidence intervals (CIs) of the multiplex were computed with IFA as the reference standard.

RESULTS

Of the 114 children (mean age 14.7 [standard deviation 2.1] years; 54 [47%] female), 18 of 114 (15.8%) were ANA positive by IFA, and 11 of 114 (9.6%) by 11-antigen multiplex assay. ANA prevalence was higher in females compared with males by both of the methods (ratios 1.6-1.9 to 1). Agreement between tests was classified as slight by kappa (κ=0.177 [95% CI -0.051, 0.406]). The multiplex immunoassay had sensitivity of 22.2% (95% CI 6.4, 47.6) and specificity of 92.7% (95% CI 85.6, 97.0), and failed to capture 3 of 4 (75%) of the high-titer (≥1:1280) IFA-positives.

CONCLUSION

Up to 15% of children in this general population cohort were ANA positive, with a higher rate of positivity among females according to both assay methods. Substantial discordance in ANA results was found between IFA and multiplex methods, even for high-titer IFA positives. These findings underscore the need to sufficiently account for assay characteristics when interpreting ANA test results, and support IFA as the more appropriate assay for studies of subclinical autoimmunity.

Recognition of the dense fine speckled (DFS) pattern remains challenging: results from an international internet-based survey

PURPOSE

The dense fine speckled (DFS) pattern as detected by indirect immunofluorescence (IIF) on HEp-2 cells has been associated with several inflammatory diseases but is most commonly observed in individuals that do not have an antinuclear antibody (ANA)-associated rheumatic disease and even in apparently healthy individuals. Consequently, the accurate identification and correct reporting of this IIF pattern is of utmost importance and accordingly has been recognized by several international study groups for the detection of ANA. Furthermore, the DFS IIF pattern has recently been recommended as a competency level recognition pattern by the International Consensus on Antinuclear Antibody (ANA) Pattern (ICAP, http://www.anapatterns.org/ ) Committee. The objective of this study was to use an internet-based survey to assess how accurately the DFS IIF pattern was recognized by experienced technologists.

METHODS

High-resolution digital IIF images were captured using the automated IIF NOVA View instrument (Inova Diagnostics, San Diego, CA). Ten images were posted in an anonymous, international, internet-based interpretive survey. Two hundred and thirty IIF technologists were invited to participate. Four of the images in the survey were from previously characterized serum samples with classical ANA IIF patterns (nucleolar, centromere, homogeneous, and speckled) and two of the images were from samples with a DFS IIF ANA pattern and isolated anti-DFS70 antibodies as determined by a chemiluminescence immunoassay. The remaining four images were from sera with the classic IIF ANA patterns referred to above and mixed with a monospecific anti-DFS70-positive sample. The survey included multiple choice selections: homogeneous, DFS, centromere, nucleolar, speckled, other, or unrecognizable.

RESULTS

125 of the 230 participants who completed the survey had diverse levels of experience in IIF pattern recognition on HEp-2 cells ranging from <1 year to >10 years of experience (average >10 years). Participants had a high concordance in correctly classifying the classical ANA IIF patterns: ranging from 95.2 % for centromere to 74.4 % for nucleolar patterns. The unmixed DFS pattern was recognized with significantly lower accuracy (~50 %; p < 0.05). However, less than 10 % correctly identified mixed patterns derived from the sera containing both clinically relevant ANA and anti-DFS70 antibodies.

CONCLUSIONS

Recognizing the DFS ANA IIF pattern and mixed IIF patterns composed of DFS + clinically relevant ANA patterns poses a significant challenge. Consequently, it seems imperative that DFS-specific immunoassays should be used to confirm the presence of anti-DFS70 antibodies before definitive results are reported to physicians.

Anti-DFS70 antibodies detected by immunoblot methods: A reliable tool to confirm the dense fine speckles ANA pattern

BACKGROUND

Autoantibodies to the DFS70 (dense fine speckles 70) protein have been identified among the antinuclear antibodies (ANA) in patients with various disorders. However, the ANA test in indirect immunofluorescence (IIF) is not a reliable method to identify anti-DFS70 antibodies. We undertook this study to evaluate the diagnostic performance of two new immunoblot methods for the detection of anti-DFS70 antibodies and to investigate whether their different DFS70 antigen composition could affect diagnostic accuracy in detecting anti-DFS70 antibodies.

METHODS

62 samples showing a DFS70 staining pattern by IIF were tested by dot blot (Alphadia) and line blot (Euroimmun) methods. The dot blot method employs a truncated sequence of the DFS70 antigen (residues 349-435), while the line blot uses the full-length protein (aa 1-530). The 62 samples were previously assayed by a chemoluminescent (CLIA) method also using a truncated antigen (aa 349-435): 27 were CLIA positive and 35 were CLIA negative. 120 sera from subjects with infectious diseases were used as controls.

RESULT

Both immunoblot methods were positive in the 27 IIF/CLIA positive samples; in addition, the Alphadia dot blot identified another seven DFS70 samples and the Euroimmun line blot was positive in five samples that were negative by CLIA. Among the 120 control samples, two false positives were recorded for the CLIA method, six for the Alphadia method and four for the Euroimmun method. Therefore, in this selected series of samples, sensitivity and specificity were 43.5% and 98.3% for the CLIA method, 54.8% and 95% for the dot blot and 51.6% and 96.6% for the line blot, respectively.

CONCLUSIONS

Because of great inconsistency in assessing the DFS70 pattern using the ANA-IIF test, specific assays should be used to confirm anti-DFS70 antibodies. The results of this study show that there is no difference in the overall diagnostic accuracy among methods that use the truncated or the full-length DFS70 antigenic sequence and that it is likely that antibodies directed against antigens other than DFS70 may be responsible for producing a DFS70-like ANA-IIF pattern.

Humoral and Cellular Autoreactivity to Epidermal Proteins in Atopic Dermatitis

Atopic dermatitis (AD), a chronic relapsing inflammatory disease of the skin, is an important public health concern affecting 10-20 % of children worldwide. The etiology and pathogenesis of AD involve the interplay of genetic and environmental factors, including abnormalities in skin integrity and a skewed immune system usually driven by a Th2 phenotype in childhood with a switch to Th1 in the chronic phase of disease. Children and adults with AD commonly have elevated IgE levels directed to multiple different antigens, including aeroallergens, food allergens, and microbial proteins. IgE targeting self-antigens from epidermal proteins have been detected in up to 91 % of patients, particularly in severe persistent AD. It has been suggested that the occurrence of autoreactivity develops in early childhood. However, it is not clear yet if autoreactive IgEs in patients with AD are pathogenic or just an epiphenomenon. The fact that these autoantibodies are associated with severity and are not present in other allergic or skin diseases favors the pathogenicity of IgE-mediated autoreactivity in AD. In this review, we evaluate the pathogenesis of AD and the emerging role of autoreactivity to various keratinocyte antigens involving both the humoral and cellular components of the immune system.