Decoding the DFS70 Pattern: A Conversation with Dr. Marvin J. Fritzler on Autoimmune Testing
In this interview, Dr. Marvin Fritzler , founder of MitogenDx and Professor Emeritus at the University of Calgary, discusses the significance of the DFS70 pattern in autoimmune testing. With over 35 years of leadership in this field, Dr. Fritzler shares insights into methods for detecting the DFS IFA pattern and its clinical implications.
The conversation explores common clinical scenarios, the role of DFS70 in differential diagnosis, and ongoing advancements in autoimmune diagnostics. Dr. Fritzler concludes with advice for healthcare providers and patients interpreting DFS70-related test results, providing a concise overview of the evolving field of precision health.
Dr. Fritzler, the founder of MitogenDx, has served as its Director for over 35 years. In addition to Mitogen, Dr. Fritzler is Professor Emeritus at the University of Calgary, Cumming School of Medicine. Receiving his PhD in Cell Biology at the University of Calgary, Dr. Fritzler continued with postdoctoral research in Autoimmunity at the Scripps Clinic and Research Institute in La Jolla, CA and at the University of Colorado. His areas of expertise include autoimmune diseases, cell and molecular biology of autoantigens, and laboratory diagnostics. Under Dr. Fritzler’s leadership and driven by his passion for precision health, MitogenDx has gained recognition and provides diagnostic services on a local, national, and international scale.
PSG: Can you briefly explain what the DFS70 pattern in autoimmune testing represents, and its significance in the context of antinuclear antibody (ANA) testing?
Dr. Fritzler: The DFS70 pattern in autoimmune testing refers to the presence of anti-DFS70 antibodies, which are a subgroup of antinuclear antibodies (ANA) [1]. These antibodies produce a dense fine speckled (DFS) staining pattern when tested by an indirect immunofluorescence assay (IFA) on HEp-2 cells [2]. The presence of anti-DFS70 antibodies indicates that an individual is highly unlikely to have an active systemic autoimmune rheumatic disease (SARD) [1], although they have been reported to be associated with other diseases and malignancies [3]. However, it is important to note that further research is needed to improve the diagnostic accuracy of these clinical associations [1]. DFS70 has various physiological functions, such as protecting against apoptosis and acting as a cofactor for HIV replication [3].
It is Important to clarify two separate and somewhat related issues. The HEp-2 IFA staining pattern should be referred to as “dense fine speckled” (ICAP AC-2) not DFS70 because DFS70 is only one antibody target identified to date associated with the DFS IFA pattern. In other words, not all sera that produce the ICAP AC-2 IFA pattern have detectable anti-DFS70 antibodies [4].
Despite several attempts, other autoantibody targets have not been definitively identified [5].
PSG: What are the main methods and technologies used to detect the DFS IFA pattern in clinical laboratory testing?
Dr. Fritzler: The main methods and technologies used to detect the DFS IFA pattern in clinical laboratory testing include:
These methods and technologies play a crucial role in the accurate detection of anti-DFS70 antibodies, which helps in distinguishing individuals without systemic autoimmune rheumatic diseases from those who may require further testing and evaluation.
PSG: In what clinical scenarios or autoimmune diseases is the DFS IFA pattern commonly observed? Are there specific patient populations where it is more prevalent?
Dr. Fritzler: The DFS70 pattern is commonly observed (up to 30% of all positive HEp-2 IFA tests) in clinical laboratory referrals of patients undergoing routine ANA testing. The presence of the DFS IFA pattern alone (ICAP AC-2) is rarely associated with systemic autoimmune rheumatic disease (SARD) such as systemic lupus erythematosus unless other disease-specific antibodies are detected in the same sample[10][11]. Most reports agree that patients with the DFS IFA pattern alone do not have an active SARD, although its prevalence may vary across different patient populations and geographic/ethnic jurisdictions [12]. As noted above, the DFS IFA pattern should be confirmed by an analyte-specific solid-phase immunoassay such as immunoblot, ELISA, ALBIA or PMAT.
PSG: Can you describe the potential clinical significance of isolated DFS70 antibody presence in a patient's blood test? How does it differ from other ANA patterns associated with autoimmune diseases?
Dr. Fritzler: Unlike certain other ANA HEp-2 IFA patterns associated with SARD, the presence of the DFS IFA pattern (ICAP AC-2) alone does not indicate the presence of an active systemic autoimmune rheumatic disease (SARD). Hence, accurately recognizing the isolated DFS AC-2 IFA ANA pattern can provide reassurance to patients that an active SARD is unlikely, thus tempering the need for tertiary care referrals and further extensive and costly investigation for a SARD [13]. It is important to note that isolated anti-DFS70 ANA patterns have been in other conditions, such as rheumatoid arthritis (who also have rheumatoid factor and anti-cyclic citrullinated peptide antibodies), organ-specific autoimmune diseases, allergic diseases, and hematological disorders [14].
PSG: What role does the DFS IFA pattern play in the diagnosis and management of autoimmune diseases, if any?
Dr. Fritzler: Since anti-DFS70 antibodies have been proposed as a marker to exclude an active systemic autoimmune rheumatic disease (SARD) [15], the DFS70 IFA pattern and confirmation of anti-DFS70 antibodies can play a significant role in the diagnosis and management of SARD. However, further research is needed to improve diagnostic accuracy and further our understanding of the ‘bandwidth’ of associated conditions [16]. There is speculation that anti-DFS70 antibodies may ‘protect’ against diseases such as SARD [17].
PSG: How does the clinical context and patient history impact the interpretation of DFS70 results in autoimmune testing?
Dr. Fritzler: The clinical context and patient history play a crucial role in interpreting anti-DFS70 results in autoimmune testing [18]. The DFS70 pattern is commonly observed in clinical laboratory referrals for routine ANA testing, but is rarely associated with systemic autoimmune rheumatic diseases (SARD) unless there is additional clinical evidence or evidence of other disease-specific antibodies [19]. Therefore, if a patient presents with a clinical history or symptoms that are not suggestive of SARD, the presence of isolated anti-DFS70 antibodies may not require urgent or emergent medical referral to a specialist [20]. However, if a patient has clinical features that suggest autoimmune disease, further testing and clinical evaluation are necessary [18]. Therefore, the clinical context including a thorough patient history should be taken into account when interpreting anti-DFS70 results in autoimmune testing.
PSG: Are there specific challenges or misconceptions related to DFS70 testing and interpretation that you've encountered in your laboratory?
Dr. Fritzler: Remarkable inter-observer variation of accurately detecting and reporting the anti-DFS IFA pattern has been reported [21]. The HEp-2 IFA staining pattern (ICAP AC-2) is often (mis-)labeled as a “homogeneous” or a “homogeneous / mixed speckled” pattern, an issue which ICAP is currently proposing criteria to distinguish the “true AC-2 pattern” from these IFA ‘look-alikes’. Of note, anti-DFS can also mask other HEp-2 IFA patterns.
PSG: Can you discuss the importance of differential diagnosis when dealing with patients who exhibit the DFS IFA pattern in their ANA test results?
Dr. Fritzler: The DFS IFA pattern in ANA test results plays a significant role in the diagnosis and management of autoimmune diseases, particularly in excluding SARD [21]. While the presence of anti-DFS70 antibodies often indicates the absence of an active SARD, it is crucial to consider the clinical context and patient history for accurate interpretation [22]. Developing a differential diagnosis becomes essential when dealing with patients exhibiting the DFS HEp-2 IFA pattern or having the anti-DFS70 antibody since it is not specific to any particular autoimmune disease [22]. Further investigations, such as tests for other disease-specific autoantibodies, should be considered to evaluate the possibility of other pathologies or associated conditions [23]. Differential diagnosis helps ensure appropriate management plans for patients based on their specific condition.
Over the years, the understanding and interpretation of DFS IFA patterns in autoimmune diagnostics has undergone a significant revolution [24]. Initiatives such as those led by ICAP (International Consensus on Antinuclear Antibody Patterns) and other organizations have played a crucial role in standardizing and harmonizing anti-DFS70 and other autoantibody testing [25]. One notable advancement is the availability of an anti-DFS70 reference standard from PSG (Plasma Services Group), providing a benchmark for accurate testing [26].
Despite these advancements, there is ongoing work to provide clarity, particularly concerning patterns that resemble AC-2 (DFS) [27]. ICAP has been actively addressing this issue, with recent discussions in Dresden 2023 indicating the potential introduction of a new HEp-2 IFA pattern designated AC-30 which brings further clarity to IFA staining features unique to anti-DFS70 such as irregular staining within the nucleus and along the outer edge of the nuclear envelope. The differentiation of these features from HEp-2 IFA patterns associated with other autoantibody specificities, such as antibodies to nucleosomes (characterized by smooth staining within the nucleus and the nuclear envelope region), is expected to contribute to a more precise and nuanced interpretation of anti-DFS IFA patterns in autoimmune diagnostics.
PSG: Are there any ongoing research or technological advancements related to DFS70 and autoimmunity that you find particularly exciting or promising?
Dr. Fritzler: Anti-DFS70 antibody testing kits are increasingly available as stand-alone assays and incorporated within multi-analyte arrays. Other issues that need clarification is when other autoantibodies accompany anti-DFS-70, such as few nuclear dots (some of which are directed against anti-p80 coilin) [28], does that alter the clinical correlation?
In addition, more directed studies of DFS70 antibodies are needed in elderly and children.
PSG: Could you share any real-world case studies or clinical scenarios where the DFS70 pattern played a significant role in a patient's diagnosis or management?
Dr. Fritzler: In a ‘real-world’ clinical scenario, the significance of the anti-DFS70 pattern in patient diagnosis and management was explored through a study conducted in a central triage (CT) system [29][30]. The study focused on patients referred to rheumatologists due to a positive HEp-2 IFA (ANA) test result. Out of 15,357 patients referred through the CT system, 643 (4.1%) were referred due to a positive ANA, and 263 (40.9%) of these ANA-positive patients were evaluated by certified rheumatologists. The outcomes revealed a diverse landscape of autoantibody specificities, with anti-Ro52/TRIM21 being the most frequently detected autoantibody. Notably, approximately 15.1% of ANA-positive archived sera showed positivity for anti-DFS70, and 91.2% of these cases did not exhibit clinical evidence for an ANA-associated rheumatic disease (AARD). This study provides valuable insights into the utility of autoantibody testing in a CT system, emphasizing the nuanced approach needed for ANA-positive cases and highlighting the specific role of anti-DFS70 in delineating clinical outcomes.
PSG: How does your laboratory handle confirmatory testing or further investigation when the DFS70 pattern is detected in ANA testing?
Dr. Fritzler: We do not routinely reflex a HEp-2 IFA DFS pattern. We provide solid-phase immunoassay testing for anti-DFS-70 on request from clinicians.
PSG: In your experience, what is the best approach for healthcare providers to communicate the significance of DFS70 results to patients and other healthcare professionals?
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Dr. Fritzler: In a 2021 paper from von Muhlen, C [31], the team emphasizes the necessity for standardized reporting of results from the anti-nuclear antibodies-indirect immunofluorescence assay (anti-cell antibodies test) on HEp-2 cell substrates. Drawing insights from practices observed in 118 laboratories across 68 countries, the International Consensus on ANA Patterns (ICAP) initiative proposes a comprehensive model for the HEp-2 IFA Test Report. The focus is on enhancing the clinical utility of laboratory findings and streamlining communication with clinicians. The proposed report format includes essential elements such as endpoint titers, immunofluorescence patterns, anti-cell (AC) nomenclature, remarks on follow-up or reflex testing, and adherence to ISO 15,189 directives. Special considerations are addressed, encompassing screening dilutions, cytoplasmic patterns, and reporting different titers corresponding to multiple patterns or autoantibodies. The paper advocates for a subtitle, "Anti-Cell Antibodies Test," gradually replacing the outdated ANA nomenclature, and underscores the importance of collating and harmonizing clinical information provided by laboratories globally.
PSG: Are there any educational or training resources you would recommend for healthcare providers who want to improve their understanding of DFS70 and autoimmune diagnostics?
Dr. Fritzler: I would recommend healthcare providers explore the resources available on the International Consensus on ANA Patterns (ICAP) website [32], which provides valuable insights into the field of autoimmune diagnostics and HEp-2 IFA patterns. Additionally, participating in HEp-2 IFA training courses can enhance their proficiency. However, there might not be specific courses or resources exclusively focused on DFS IFA staining patterns or anti-DFS70 testing. It's advisable to stay updated on emerging educational materials within the field.
PSG: What advice would you offer to patients who have received DFS70-related test results and are seeking more information or guidance?
Dr. Fritzler: For reassurance, find a clinician who understands the anti-DFS70 test result. Interestingly, in response to the question “what is the significance of a positive anti-DFS70 test result” ChatGPT responds:
“Anti-DFS-70 (anti-dense fine speckled 70) is an autoantibody associated with certain autoimmune diseases, particularly with autoimmune rheumatic diseases. These autoantibodies are often detected in the laboratory through a test called the indirect immunofluorescence (IIF) method, where a specific pattern known as "dense fine speckled" is observed under a microscope.
The significance of anti-DFS-70 antibodies lies in their association with specific autoimmune conditions, including:
It's important to note that the presence of anti-DFS-70 antibodies alone does not provide a definitive diagnosis of a specific autoimmune disease. The interpretation of test results should be done in the context of a patient's clinical symptoms, medical history, and additional laboratory tests.
Furthermore, anti-DFS-70 antibodies have gained attention because their presence has been associated with a lower likelihood of having other specific autoimmune diseases, particularly when observed in isolation. In some cases, the identification of these antibodies may help guide healthcare professionals in the diagnostic process.
As research in autoimmunity continues, the understanding of the significance of specific autoantibodies, including anti-DFS-70, may evolve, and healthcare professionals will continue to refine their interpretation and clinical application. If you or someone you know has been tested positive for anti-DFS-70 antibodies, it is crucial to consult with a healthcare provider for a comprehensive evaluation and appropriate management.[33]”
Clinical Laboratory Director at Incite Health
1yGreat info as always, Marv!
Professor at Universidade do Vale do Itajaí,UNIVALI, Brazil
1yGreat
Innovative biotechnology leader specializing in discovery, development and commercialization of research and diagnostic biomarkers and technologies.
1yNice article.. misinterpretation of DFS70 pattern or not detecting the concealed patterns behind AC-02 can create false negative results for patients. Solid phase assays take away the interpretation challenges associated with HEP-2 IFA, but each technology presents it's own benefits at screening and confirmation stages. Applaud all that ICAP and PSG is doing to raise the awareness. Nice article Marvin!!
Jefe Depto de Inmunologia y Reumatologia en Universidad de Guadalajara
1yMarvin, nice presentation!!
SVP R&D/BD at Werfen; Co-founder of Precision Medicine in Autoimmunity; Scientific Author
1yNice article on DFS70