Distinctive features of positive anti-cell antibody tests (indirect immunofluorescence on HEp-2 cells) in patients with non-autoimmune diseases

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.

The Role of Autoantibody Testing in Modern Personalized Medicine

Personalized medicine (PM) aims individualized approach to prevention, diagnosis, and treatment. Precision Medicine applies the paradigm of PM by defining groups of individuals with akin characteristics. Often the two terms have been used interchangeably. The quest for PM has been advancing for centuries as traditional nosology classification defines groups of clinical conditions with relatively similar prognoses and treatment options. However, any individual is characterized by a unique set of multiple characteristics and therefore the achievement of PM implies the determination of myriad demographic, epidemiological, clinical, laboratory, and imaging parameters. The accelerated identification of numerous biological variables associated with diverse health conditions contributes to the fulfillment of one of the pre-requisites for PM. The advent of multiplex analytical platforms contributes to the determination of thousands of biological parameters using minute amounts of serum or other biological matrixes. Finally, big data analysis and machine learning contribute to the processing and integration of the multiplexed data at the individual level, allowing for the personalized definition of susceptibility, diagnosis, prognosis, prevention, and treatment. Autoantibodies are traditional biomarkers for autoimmune diseases and can contribute to PM in many aspects, including identification of individuals at risk, early diagnosis, disease sub-phenotyping, definition of prognosis, and treatment, as well as monitoring disease activity. Herein we address how autoantibodies can promote PM in autoimmune diseases using the examples of systemic lupus erythematosus, antiphospholipid syndrome, rheumatoid arthritis, Sjögren syndrome, systemic sclerosis, idiopathic inflammatory myopathies, autoimmune hepatitis, primary biliary cholangitis, and autoimmune neurologic diseases.

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.

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.

Interkit Reproducibility of the Indirect Immunofluorescence Assay on HEp-2 Cells Depends on the Immunofluorescence Reactivity Intensity and Pattern

Introduction

The indirect immunofluorescence assay on HEp-2 cells (HEp-2/IFA) is used worldwide for screening for autoantibodies to cellular antigens. Cell culture and fixation methods influence the cell distribution of autoantigens and the preservation of epitopes. Therefore, discrepancy of results obtained using different HEp-2/IFA kits (interkit nonreproducibility) is a common phenomenon in the clinical laboratory routine.

Objective

This study evaluated the interkit nonreproducibility of HEp-2/IFA results using samples from patients with systemic autoimmune disease (SAD), nonautoimmune diseases (NAD), and healthy blood donors (HBD).

Methods

Serum from 275 SAD patients, 293 NAD patients, and 300 HBD were processed at 1:80 dilution using four HEp-2 kits according to the manufacturers’ instructions. Interkit reproducibility was determined for positive/negative results and patterns. The agreement of positive/negative results among kits for each sample was determined as the reactivity agreement score (RAS). The pattern reproducibility score (PRS) in each sample was calculated as a function of the number of kits showing equivalent patterns. Qualitative variables and ordinal variables were analyzed by the Chi-square and Mann-Whitney U tests, respectively.

Results

A total of 402 samples were nonreactive in all kits and were considered devoid of autoantibodies. Further analysis included the 466 reactive samples (238 SAD, 119 NAD, 109 HBD). Reactivity to the nucleus had the highest interkit reproducibility (RAS = 83.6), followed by the metaphase plate (RAS = 78.9), cytoplasm (RAS = 77.4), and nucleolus (RAS = 72.4). Interkit reproducibility was higher in SAD (RAS = 78.0) than in NAD (RAS = 70.6) and HBD (RAS = 71.3) groups. Samples with strong reactivity (++++/4 and +++/4) had higher interkit reproducibility than those with weak reactivity (+/4). In the SAD group, RAS for nuclear reactivity was 87.5% for strongly reactive samples as opposed to 4.4% for weakly reactive samples, and the same was observed for NAD and HBD samples. The most robust patterns were the centromere AC-3 (PRS = 78.4), multiple nuclear dots AC-6 (PRS = 73.6), nuclear coarse speckled AC-5 (PRS = 71.3), nuclear homogeneous AC-1 (PRS = 67.9), and the reticular cytoplasmic AC-21 (PRS = 68.6).

Conclusion

Interkit nonreproducibility in HEp-2/IFA is prevalent and occurs with the highest frequency with weakly reactive samples. International initiatives with the engagement of in vitro diagnostic industry are encouraged to promote the harmonization of the properties and performance of HEp-2/IFA commercial kits.

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.

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

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

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

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

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.

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.

Rheumatologist perspective of the Brazilian consensus for detection of auto antibodies in HEp-2 CELLS

OBJECTIVE

To evaluate the perception of rheumatologists regarding the recommendations of the Brazilian Consensus for detection of Autoantibodies (BCA) on HEp-2 Cells by Indirect Immunofluorescence assay (IFA) and how BCA recommendations help in clinical practice.

METHODOLOGY

A structured questionnaire regarding the BCA recommendations for detection and interpretations of autoantibodies in HEp-2 cells was applied to randomly selected rheumatologists. The results were tabulated using the Microsoft® Excel program, expressed as a simple percentage and the dichotomous data were analyzed using the Chi-square test and the Epi Info® program.

RESULTS

Four hundred fuorteen rheumatologists participated in the study: 70% of them considered their knowledge of the HEp-2 IFA test satisfactory or excellent, and 43% said they knew the BCA recommendations in general, without distinguishing the edition of the BCA to which they refer. The Revista Brasileira de Rheumatologia/Advances in Rheumatology was the means of dissemination most consulted by specialists (50%). According to the rheumatologists' opinion, the most relevant pattern was the homogeneous nuclear (78%) and 65% stated they were satisfied with the BCA recommendations at a level of satisfaction greater than or equal to 80%. There was no significant difference in the perception of rheumatologists from the several Brazilian geographic regions.

CONCLUSION

Brazilian rheumatologists are aware of the BCA guidelines and most are satisfied with the content published, considering that the BCA recommendations assist positively in the clinical practice. Most rheumatologists recognize the patterns associated with rheumatic autoimmune diseases and have used BCA recommendations to interpret the results of the HEp-2 IFA test.