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

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.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

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.

The influence of demography and referral medical specialty on the detection of autoantibodies to HEP-2 cells in a large sample of patients

Background

The prevalence of anti-cell autoantibodies detected by indirect immunofluorescence assay on HEp-2 cells (HEp-2-IIFA) increases with age and is higher in female sex. The number of medical specialties that use HEp-2-IIFA in the investigation of autoimmune diseases has increased lately. This study aimed to determine the prevalence and patterns of autoantibodies on HEp-2-IIFA according to demographics variables and referring medical specialties.

Methods

A retrospective analysis of the HEp-2-IIFA carried out between January and June of 2017 was performed. The International Consensus on Antinuclear Antibodies Patterns (ICAP) and the Brazilian Consensus on Autoantibodies were used for patterns definition on visual reading of the slides. Anti-cell (AC) codes from ICAP and Brazilian AC codes (BAC) were used for patterns classification.

Results

From 54,990 samples referred for HEp-2-IIF testing, 20.9% were positive at titer ≥ 1/80. HEp-2-IIFA positivity in females and males was 24% and 12%, respectively (p < 0.0001). The proportion of positive results in the 4 age groups analyzed: 0–19, 20–39, 40–59, and ≥ 60 years was 23.3, 20.2, 20.1, and 22.8%, respectively (p < 0.0001). Considering all positive sera (n = 11,478), AC-4 nuclear fine speckled (37.7%), AC-2 nuclear dense fine speckled (21.3%), BAC-3 nuclear quasi-homogeneous (10%) and mixed/composite patterns (8.8%) were the most prevalent patterns. The specialties that most requested HEp-2-IIFA were general practitioner (20.1%), dermatology (15%), gynecology (9.9%), rheumatology (8.5%), and cardiology (5.8%). HEp-2-IIFA positivity was higher in patients referred by rheumatologists (35.7% vs. 19.6%) (p < 0.0001). Moderate (46.4%) and high (10.8%) titers were more observed in patients referred by rheumatologists (p < 0.0001). We observed a high proportion of mixed and cytoplasmic patterns in samples referred by oncologists and a high proportion of BAC-3 (nuclear quasi-homogeneous) pattern in samples referred by pneumologists.

Conclusions

One-fifth of the patients studied were HEp-2-IIFA-positive. The age groups with more positive results were 0–19 and ≥ 60 years. AC-4, AC-2, BAC-3 and mixed/composite patterns were the most frequent patterns observed. Rheumatologists requested only 8.5% of HEp-2-IIFA. Positive results and moderate to high titers of autoantibodies were more frequent in patients referred by rheumatologists.

Antinuclear Autoantibodies in Health: Autoimmunity Is Not a Synonym of Autoimmune Disease

The incidence of autoimmune diseases is increasing. Antinuclear antibody (ANA) testing is a critical tool for their diagnosis. However, ANA prevalence in healthy persons has increased over the last decades, especially among young people. ANA in health occurs in low concentrations, with a prevalence up to 50% in some populations, which demands a cutoff revision. This review deals with the origin and probable physiological or compensatory function of ANA in health, according to the concept of immunological clearance, theory of autoimmune regulation of cell functions, and the concept of functional autoantibodies. Considering ANA titers ≤1:320 as a serological marker of autoimmune diseases seems inappropriate. The role of anti-DFS70/LEDGFp75 autoantibodies is highlighted as a possible anti-risk biomarker for autoimmune rheumatic disorders. ANA prevalence in health is different in various regions due to several underlying causes discussed in the review, all influencing additive combinations according to the concept of the mosaic of autoimmunity. Not only are titers, but also HEp-2 IFA) staining patterns, such as AC-2, important. Accepting autoantibodies as a kind of bioregulator, not only the upper, but also the lower borders of their normal range should be determined; not only their excess, but also a lack of them or "autoimmunodeficiency" could be the reason for disorders.

The Possible Effect of B-Cell Epitopes of Epstein-Barr Virus Early Antigen, Membrane Antigen, Latent Membrane Protein-1, and -2A on Systemic Lupus Erythematosus

This study was aimed to evaluate the role of B-cell epitopes of Epstein-Barr virus (EBV) Early antigen protein D (EA), envelope glycoprotein GP340/membrane antigen (MA), latent membrane protein (LMP)-1, and LMP-2A in systemic lupus erythematosus (SLE). B-cell epitopes were predicted by analyzing secondary structure, transmembrane domains, surface properties, and homological comparison. 60 female mice were randomized equally into 12 groups: 1-10 groups were immunized by epitope peptides (EPs) 1-10, respectively, while 11 and 12 groups were PBS and Keyhole limpet hemocyanin (KLH) control groups. Immunoglobulin G (IgG) and autoantibody to nuclear antigen (ANA) concentrations in mice serum were determined at week 8. Indirect levels of EP1-10 were further detected by enzyme-linked immuno sorbent assay (ELISA) in 119 SLE patients and 64 age- and gender-matched health controls (HCs). 10 probable EBV EA, MA, LMP-1, and LMP-2A B-cell epitopes related to SLE self-antigens were predicted and corresponding EP1-10 were synthesized. IgG concentrations at week 8 were increased in EP1-10 and KLH groups compared with PBS group in mice; while ANA levels were elevated in only EP1-4, EP6-7, and EP10 groups compared to KLH group by ELISA, and ANA-positive rates were increased in only EP1, EP2, EP4, EP6, and EP10 groups by indirect immunofluorescence assay. EP1-4, EP6, and EP10 indirect levels were increased in SLE patients than HCs, while EP1, EP3, EP6, and EP9 were correlated with SLE disease activity index score. In conclusion, EBV EA, MA, LMP-1, and LMP-2A B-cell EPs increased SLE-related autoantibodies in mice, and their indirect levels might be served as potential biomarkers for SLE diagnosis and disease severity.