Autoantibody detection with indirect immunofluorescence on HEp-2 cells: starting serum dilutions for systemic rheumatic diseases

Clinical usefulness of anti-nuclear antibody in childhood: real-world experience at a tertiary care center : Usefulness of ANA in pediatric autoimmune diseases

We evaluated the reasons for requesting anti-nuclear antibody (ANA) analysis in clinical practice at a tertiary center and the performance of ANA in pediatric autoimmune diseases. Patients under 18 years of age who underwent ANA testing for various symptoms between 2013 and 2017 were included. We retrieved data from medical records, including demographic and clinical characteristics, diagnoses, ANA results, titers, and staining patterns. The performance assessment tools were calculated according to the ANA titer for autoimmune diseases. Risk factors for autoimmune diseases in ANA-positive patients were evaluated using logistic regression analysis. Changes in ANA titer and seroconversion were evaluated using repeated ANA analyses. A total of 3812 patients underwent ANA. Medical records of 3320 patients were obtained. The rate of ANA positivity was 27.4%. ANA was requested most frequently because of musculoskeletal findings in 1355 patients (40.8%). Juvenile idiopathic arthritis (n = 174, 20.2%) was the most common diagnosis in ANA-positive patients, followed by systemic lupus erythematosus (n = 52, 6%). For autoimmune diseases, a titer of ≥ 1:100, a sensitivity of 40.1%, and a specificity of 77.1% were observed. At a titer ≥ 1:1000, the sensitivity and specificity were 24.1% and 89%, respectively. Homogeneous staining was an additional risk factor for autoimmune diseases in ANA-positive patients by multivariate logistic regression analysis (OR [95% CI]: 4.562 [3.076-6.766], p < 0.001).    Conclusion: Our results revealed that the performance of the ANA test in diagnosing autoimmune diseases in pediatric clinical practice was poor. Therefore, clinical findings should be carefully evaluated before ANA testing is performed. What is Known: • ANA can be detected in systemic autoimmune rheumatic diseases. • The diagnostic role of ANA is controversial, especially in childhood. What is New: • One in four patients who requested the ANA test had an autoimmune disease. • Less than half of patients with an autoimmune disease had ANA positivity.

Anti-nuclear antibody testing in children: How much is really necessary?

BACKGROUND

Anti-nuclear antibody (ANA) testing is most commonly ordered by general pediatricians to evaluate children with musculoskeletal system complaints. Given the limited utility of the test, we aimed to estimate the effectiveness of ordering ANA testing in childhood.

METHODS

Children referred to our department to be examined due to positive ANA findings between 2008 and 2020 were included in the study. Those with less than one-year follow-up period, those with previously known rheumatic or autoimmune disease, and those diagnosed as an autoimmune and/or rheumatic disease at the first visit were excluded. Data were obtained from their medical records, retrospectively. The parents of all of the patients were called via phone, data were verified, and missing information was collected.

RESULTS

Three hundred and fifty-eight patients (230 females) were eligible for the study. The median age of positive ANA findings was 9.31 (1.3-17.86) years and the median follow-up duration was 4.85 (1-11.91) years. Most of the patients had no underlying disease (n = 337, 94.1%). The most common reason for ordering ANA testing was to evaluate musculoskeletal system symptoms (n = 225, 62.8%). None of our patients referred to us due to positive ANA findings developed any autoimmune conditions or ANA associated rheumatic disease. Hypermobility syndrome is the most common final diagnosis among our ANA-positive patients.

CONCLUSION

We suggest that instead of using it as a screening tool, ANA testing should be performed only if there is a strong suspicion of autoimmune diseases or certain rheumatic conditions, such as systemic lupus erythematosus.

Differential clinical features of patients with clinically amyopathic dermatomyositis who have circulating anti-MDA5 autoantibodies with or without myositis-associated autoantibodies

BACKGROUND

Anti-melanoma differentiation-associated gene 5 (MDA5) autoantibodies have been identified as myositis-specific autoantibodies that are often associated with clinically amyopathic dermatomyositis (CADM) and a poor prognosis due to rapidly progressive interstitial lung disease (RP-ILD) in East Asian patients. Besides anti-MDA5 autoantibodies, patients with CADM may have myositis-associated autoantibodies (MAAs), which characterize other connective tissue diseases such as rheumatoid arthritis and Sjögren's syndrome. However, the clinical significance of the coexistence of anti-MDA5 autoantibodies and MAAs in patients with CADM remains unclear.

METHODS

We retrospectively analyzed 24 patients with CADM who had anti-MDA5 autoantibodies. Their clinical phenotypes including laboratory test results, high-resolution lung computed tomography data, response to therapy, and prognosis were compared between those who were positive and negative for MAAs, such as antinuclear antibody (ANA), anti-cyclic citrullinated peptide (CCP), anti-SSA, and anti-SSB antibodies.

RESULTS

Among 24 patients, 9 (37.5%) additionally had at least one of the MAAs examined in this study: 1 patient was positive for ANA, 5 for anti-CCP, 5 for either anti-SSA or anti-SSB, 1 for anti-cardiolipin, and 1 for anti-Scl-70. Although all anti-MDA5-positive patients with CADM had ILD, the MAA-positive patients showed a lower risk of developing RP-ILD (p = 0.03), a more favorable response to combination therapy of corticosteroids and immunosuppressive agents, and a lower mortality rate than patients with no MAAs (p = 0.03).

CONCLUSIONS

Our data suggest that anti-MDA5-positive patients with CADM who also have MAAs have a better prognosis than those without MAAs; thus, anti-MDA5 autoantibodies by themselves may not be strong predictors of worse clinical outcomes in patients with CADM. Coexistent MAAs could be biomarkers for a favorable prognosis in anti-MDA5-positive patients with CADM.

Newly diagnosed immune thrombocytopenia adults: Clinical epidemiology, exposure to treatments, and evolution. Results of the CARMEN multicenter prospective cohort

The clinical epidemiology of immune thrombocytopenia (ITP) is not well known in adults. This study was aimed at assessing the clinical epidemiology of incident ITP adults, the factors associated with chronicity and exposure to treatments. This study was conducted in the CARMEN registry, a multicentric prospective cohort aimed at including all newly diagnosed ITP adults in the French Midi-Pyrénées region, South of France (3 million inhabitants) from June 2013. Descriptive analyses and multivariate logistic regression models were conducted. Out of 121 newly diagnosed ITP until December 2014, 113 patients were followed in the region and gave informed consent. Median age was 65 years. Half of the patients were female, 20.3% had a secondary ITP, 50.4% had a Charlson's score ≥1, median platelet count was 17 × 10⁹ /L; 50.9% had bleeding symptoms, including 2 severe gastrointestinal tract and 1 intracranial bleedings; 21.4% had another autoimmune disease and 20.3% experienced an infection within the six weeks before ITP onset. Persistency and chronicity rates were 68.2% and 58.7%, respectively. Antinuclear antibodies were associated with chronicity (OR: 2.89, 95% CI: 1.08-7.74). Sixty-eight (60.2%) patients were treated during the week following the diagnosis. Factors associated with the use of intravenous corticosteroids were secondary ITP and high bleeding score. Those associated with the use of intravenous immunoglobulin (IVIg) were a high bleeding score and low platelet count. In conclusion, severe bleeding is rare at ITP onset. Associated autoimmune diseases and recent infections were frequent. Antinuclear antibodies seem predictors of chronicity. Intravenous corticosteroids and IVIg were frequently used.

The Use of Poly-L-Lysine as a Capture Agent to Enhance the Detection of Antinuclear Antibodies by ELISA

Antibodies to nuclear antigens (antinuclear antibodies or ANAs) are the serological hallmark of systemic lupus erythematosus (SLE). These antibodies bind diverse nuclear antigens that include DNA, histones and non-histone proteins as well as complexes of proteins with DNA and RNA. Because of the frequency of ANA expression in SLE, testing is an important component of clinical evaluation as well as determination of eligibility for clinical trials or utilization of certain therapies. Immunofluorescence assays have been commonly used for this purpose although this approach can be limited by issues of throughput, variability and difficulty in determining positivity. ELISA and multiplex assays are also useful approaches although these assays may give an incomplete picture of antibodies present. To develop a sensitive and quantitative ANA assay, we have explored an ELISA platform in which plates are pre-coated with a positively charged nucleic acid binding polymer (NABP) to increase adherence of antigens containing DNA or RNA. As a source of antigens, we have used supernatants of Jurkat cells undergoing apoptosis in vitro. As results presented show, a poly-L-lysine (PLL) pre-coat significantly enhances detection of antibodies to DNA as well as antigens such as histones, SSA, SSB and RNP. Comparison of the ELISA assay with the PLL pre-coat with a multiplex assay using the BioPlex^® 2200 system indicated good agreement in results for a panel of lupus sera. Together, these studies indicate that a pre-coat with a positively charged polymer can increase the sensitivity of an ANA ELISA using as antigens molecules released from dead and dying cells. This assay platform may facilitate ANA testing by providing an ensemble of antigens more similar in composition and structure with antigens present in vivo, with a NABP promoting adherence via charge-charge interactions.

Prevalence of antinuclear antibodies in healthy Lebanese subjects, 2008-2015: a cross-sectional study involving 10,814 subjects

Antinuclear antibodies (ANA) are found at varying frequencies in healthy populations, depending on geographical location and ethnic background of participants. The main objective of this study was to determine the prevalence of ANA in healthy Lebanese population in the period 2008-2015. Study subjects comprised 10,851 individuals (3311 males and 7503 females). ANA positivity was determined using immunofluorescence on HEp-2 cells. The prevalence of positive ANA test at a titer of ≥1:100 was 26.4 %, with 696 individuals (6.4 %) having titers exceeding 1:100. Most ANA-positive cases were recorded between 2013 and 2015, which reflected increased assay sensitivity. ANA positivity was associated with increased age and with female gender. Significant increases in ANA positivity were seen with advanced age, with steady increases from the 30- to 40-year age group through the >70-year age group, with significantly higher prevalence noted in female participants. There was a steady and significant reduction in the number of ANA-positive cases with higher ANA titers, which ranged from 20.0 % (1/100) to 3.7 % (1/320), 1.7 % (1/640), and 1.1 % (1/1000). While 45 % of low ANA titer was seen in 31-60-year age category, compared with 19.8 % for 61+ year category, the distribution of high ANA titer was more uniform between 31+ year age categories, which ranged from 11.4 % (31-40 years) to 12.4 % (>70 years). This was consistently and significantly higher in female participants. The prevalence and distribution of ANA among Lebanese individuals were comparable to the rates established for Western countries and confirm the contribution of female gender and advanced age to ANA positivity.

Anti-ENA profiles related with anti-SS-A/Ro. The detection of Ro52 and Ro60 according to the presence of SS-B/La, and ANA pattern and titer

Anti-Ro52 (Ro52) and anti-Ro60 (Ro60) antibodies are associated with different clinical entities. We investigated their relationship with the presence of anti-SS-B/La (SSB) antibody, the pattern and titer of antinuclear antibody (ANA), and the variations in antibody profiles related with anti-SS-A/Ro (SSA) positivity. Our aim was to develop a strategy to increase the efficiency of anti-extractable nuclear antigen (ENA) determinations. Statistical analyses were based on the Chi-squared test for categorical variables, the Mann-Whitney U test to compare profiles, and the odds ratio (OR) and 95% confidence interval (95% CI) to estimate the risk of variability. We analyzed 800 SSA-positive samples with Ro52 or Ro60 reactivity. The most frequent profiles were Ro52+Ro60+SSB (n=349, 43.6%); Ro52+Ro60 (n=126, 15.8%); Ro52 (n=121, 15.1%) and Ro60 (n=71, 8.9%). In samples positive only for SSA and an ANA titer ≤1:640, the most likely profile was positivity for either Ro52 or Ro60, whereas when the ANA titer was >1:640, positivity for both Ro52 and Ro60 simultaneously was more likely (p<0.001). In samples positive for both SSA and SSB, the most likely profile was Ro52+Ro60+SSB regardless of the ANA titer (p=0.001). When only SSA was positive and the ANA staining pattern was nucleolar, centromeric or cytoplasmic, Ro52 positivity was most likely (p<0.001). When both SSA and SSB were positive, both Ro52 and Ro60 were likely to be positive regardless of the ANA staining pattern. In 28.7% of the patients the profile was variable. Variability was significantly greater in those with the SSA profile (23/67) than with the SSA+SSB profile (15/105; OR=1.9, 95% CI=1.1-3.3; p=0.025), and the difference in variability was greatest between the Ro52+Ro60 profile (8/23) and the Ro52+Ro60+SSB profile (8/68; OR=4.2, 95% CI=1.9-9.5; p<0.001). We conclude that to increase efficiency in the immunology laboratory, positivity for Ro52 and Ro60 individually or simultaneously can be deduced from SSB status and the ANA pattern and titer. In general, for the most frequent anti-ENA findings, priority should be given to retesting autoantibodies not detected in the initial analysis.

Current concepts and future directions for the assessment of autoantibodies to cellular antigens referred to as anti-nuclear antibodies

The detection of autoantibodies that target intracellular antigens, commonly termed anti-nuclear antibodies (ANA), is a serological hallmark in the diagnosis of systemic autoimmune rheumatic diseases (SARD). Different methods are available for detection of ANA and all bearing their own advantages and limitations. Most laboratories use the indirect immunofluorescence (IIF) assay based on HEp-2 cell substrates. Due to the subjectivity of this diagnostic platform, automated digital reading systems have been developed during the last decade. In addition, solid phase immunoassays using well characterized antigens have gained widespread adoption in high throughput laboratories due to their ease of use and open automation. Despite all the advances in the field of ANA detection and its contribution to the diagnosis of SARD, significant challenges persist. This review provides a comprehensive overview of the current status on ANA testing including automated IIF reading systems and solid phase assays and suggests an approach to interpretation of results and discusses meeting the problems of assay standardization and other persistent challenges.