Challenges in the Standardization of Autoantibody Testing: a Comprehensive Review

Issues in autoantibody tests used in the classification criteria for autoimmune rheumatic diseases: the laboratory autoimmunologist's perspective

Classification criteria of autoimmune rheumatic diseases are an important means to define homogenous groups of patients that can be compared across studies for clinical trials and research purposes. The measurement of autoantibodies is a relevant aspect in the definition of classification criteria, with a significant weight in the scores necessary to classify patients with autoimmune rheumatic diseases. The impact of autoantibodies has gradually increased over the years, contributing to the evolution and improvement of the classification criteria. However, these criteria often do not take into consideration how autoantibodies are measured, i.e. differences in diagnostic accuracy of the methods. This is a critical point especially when obsolete analytical methods that are no longer used in many clinical laboratories are taken into consideration. In this review we have critically examined assays and methods for the determination of autoantibodies that are (or could be) included among the classification criteria of autoimmune rheumatic diseases in light of more recent evidence and technology evolution.

Reflecting on a decade of the international consensus on ANA patterns (ICAP): Accomplishments and challenges from the perspective of the 7th ICAP workshop

The International Consensus on ANA Patterns (ICAP) is an ongoing international initiative dedicated to harmonizing technical and interpretation aspects of the HEp-2 IFA test. Comprised of internationally recognized experts in autoimmunity and HEp-2 IFA testing, ICAP has operated for the last 10 years by promoting accurate reading, interpretation, and reporting of HEp-2 IFA images by professionals involved in various areas related to autoimmune diseases, such as clinical diagnostic laboratories, academic research, IVD industry, and patient care. ICAP operates through continuous information exchange with the international community and encourages the participation of younger experts from all over the world. The 7th ICAP workshop has addressed several aspects that originated from this interaction with the international community and has effectively established objective goals and tasks to be delivered over the next two years. Some of these are outlined in this article, including the planning of three audio-visual educational modules to be posted at the www.anapattern.org website, the classification of two novel HEp-2 IFA patterns, the implementation of a project dedicated to continuously updating the information on the clinical and immunologic relevance of the HEp-2 IFA patterns, and the launch of two additional branches of the HEp-2 Clinical and Immunological (HEp-2 CIC) project.

Evaluation of a New Multiparametric Microdot Array-Based Immunoassay Panel for Systemic Autoimmune Disease Diagnosis

BACKGROUND

The early reliable detection and quantification of autoantibodies play an important role in autoimmune disease diagnosis and in disease-course monitoring. New technologies, such as the multiplexed determination of autoantibodies, have recently been introduced and are being adopted more frequently. The aim of this study was to evaluate the ability of a new microdot array-based multiparametric assay (ZENIT AMiDot CTD panel, A. Menarini Diagnostics, Firenze, Italy) to correctly classify patients with autoimmune rheumatic diseases (ARDs) and compare it to a fluorescence enzyme immunoassay (FEIA) for the detection of anti-ENAs.

METHODS

The study included 69 consecutive samples from patients with ARDs that were analyzed using two different methods (FEIA and AMiDot) to detect anti-CENP B and six anti-ENA antibodies: anti-Scl-70, anti-SSB/La, anti-Jo-1, anti-U1-RNP, anti-Ro52, and anti-Ro60. The control group sera came from sixty-eight blood donors. Tests were run on the automated slide processor ZENIT FLOW, and then the slides were imaged and analyzed using ZENIT fast.

RESULTS

Since the samples were selected for at least one antibody positivity with an ARD diagnosis, we did not calculate clinical sensitivity but only specificity, which was 98.53%, ranging from 90% for anti-SSB/La antibodies to 100% for anti-CENP B ones. Mean agreement among the methods assessed by Cohen's kappa was 0.816 ± 0.240.

CONCLUSIONS

The assay demonstrated good clinical performance and may be considered a valuable aid in detecting ARD patients, offering an alternative to methods such as FEIA which are largely in use today.

The role of amino acid metabolism in autoimmune hepatitis

Autoimmune hepatitis (AIH) is an inflammatory chronic liver disease with persistent and recurrent immune-mediated liver injury. The exact cause of AIH is still not fully understood, but it is believed to be primarily due to an abnormal activation of the immune system, leading to autoimmune injury caused by the breakdown of autoimmune tolerance. Although the pathogenesis of AIH remains unclear, recent studies have shown that abnormalities in amino acid metabolism play significant roles in its development. These abnormalities in amino acid metabolism can lead to remodeling of metabolic processes, activation of signaling pathways, and immune responses, which may present new opportunities for clinical intervention in AIH. In this paper, we first briefly outline the recent progress of clinically relevant research on AIH, focusing on the role of specific amino acid metabolism (including glutamine, cysteine, tryptophan, branched-chain amino acids, etc.) and their associated metabolites, as well as related pathways, in the development of AIH. Furthermore, we discuss the scientific issues that remain to be resolved regarding amino acid metabolism, AIH development and related clinical interventions, with the aim of contributing to the future development of amino acid metabolism-based as a new target for the clinical diagnosis and treatment of AIH.

A Novel In Vitro Assay Correlates Insulin Receptor Autoantibodies With Fasting Insulin in Type B Insulin Resistance

CONTEXT

Severe insulin resistance (IR) in the presence of insulin receptor autoantibodies (InsR-aAb) is known as type B insulin resistance (TBIR). Considerable progress in therapy has been achieved, but diagnosis and monitoring of InsR-aAb remains a challenge.

OBJECTIVE

This work aimed to establish a robust in vitro method for InsR-Ab quantification.

METHODS

Longitudinal serum samples from patients with TBIR at the National Institutes of Health were collected. A bridge-assay for InsR-aAb detection was established using recombinant human insulin receptor as bait and detector. Monoclonal antibodies served as positive controls for validation.

RESULTS

The novel assay proved sensitive, robust, and passed quality control. The measured InsR-aAb from TBIR patients was associated with disease severity, decreased on treatment, and inhibited insulin signaling in vitro. Titers of InsR-aAb correlated positively to fasting insulin in patients.

CONCLUSION

Quantification of InsR-aAb from serum samples via the novel in vitro assay enables identification of TBIR and monitoring of successful therapy.

Is There a Need to Undertake Conventional Gastroscopy and Biopsy When Making the Diagnosis of Coeliac Disease in Adults?

Celiac disease is a common autoimmune condition characterized by small intestinal inflammation and mucosal damage triggered by an inappropriate immune response to ingested gluten. Gastroscopy and duodenal biopsy are currently the gold standard approach to diagnosing celiac disease in adults. However, the emergence of highly accurate serological tests for celiac disease in the last 2 decades led to a change in the pediatric guidelines to diagnose celiac disease without biopsy in selected patients. Adopting this no-biopsy approach to diagnose celiac disease in adults remains controversial, but the evidence supporting it is growing.

Anti-Nuclear Antibody Quantitation: Calibration and Harmonization Adjustment via Population Interrogation

BACKGROUND

The 2019 classification criteria for systemic lupus erythematosus (SLE) includes an initial criterion requiring the presence of an antinuclear antibody (ANA), positive at a titer of at least 1:80 on HEp-2 cells, or equivalent. However, results of ANA tests performed on HEp-2 cells vary when tested in different laboratories. Calibration of ANA assays by achieving a common specificity in healthy control populations offers the possibility of achieving harmonization via population interrogation, but the expected specificity in a healthy control population is not known.

METHODS

The studies used to determine the use of ANAs performed by immunofluorescence microscopy on HEp-2 cells as the entry criterion for classification of SLE were reanalyzed by a meta-analysis to determine the expected frequency of positive ANAs in healthy control populations at serum dilutions of 1:40 and 1:80.

RESULTS

Our meta-analysis demonstrated that the expected specificity in a healthy control population of ANA performed using serum diluted 1:80 is 91.3% (CI 86.1-94.7%). The expected specificity of ANA performed at 1:40 serum dilution is 79.2% (CI 72.3-84.8%).

CONCLUSION

One approach to achieving harmonization of ANA assays from different laboratories with each other and with expected performance would involve adjusting assays so that about 10% of a healthy control population has a positive ANA when tested at 1:80 dilution, and about 20% of the healthy control population has a positive ANA when tested at 1:40 dilution. This pragmatic approach to calibration and harmonization adjustment via population interrogation offers an opportunity for individual laboratories to be aligned with each other and with ANA performance expected for consistent categorization of patients with SLE.

Anti-Golgi Antibody as a Potential Indicator for Rheumatoid Arthritis

OBJECTIVE

To reveal the relationship between anti-Golgi antibody (AGA) and clinical diseases through retrospective analysis.

METHODS

The clinical data of 584 cases testing positive for AGA in the past 11 years were collected and retrospectively analyzed.

RESULTS

AGA pattern accounted for .2% of positive ANA results. In total, 35.0% of diagnosed patients had autoimmune diseases (AID), mainly rheumatoid arthritis (RA). High-titer AGA (≧1:1000) was common in AID. In nondiagnosed patients with clinical symptoms, joint pain/muscle pain was the most common.

CONCLUSIONS

Positive AGA with high titer was closely related to RA. Joint pain/muscle pain was the most common symptom in patients who tested AGA positive. Therefore, AGA may be a key indicator of RA in the Chinese population.

Standardization and Quality Assessment Under the Perspective of Automated Computer-Assisted HEp-2 Immunofluorescence Assay Systems

The recent availability of automated computer-assisted diagnosis (CAD) systems for the reading and interpretation of the anti-nuclear antibody (ANA) test performed with the indirect immunofluorescence (IIF) method on HEp-2 cells, has improved the reproducibility of the results and initiated a process of harmonization of this test. Furthermore, CAD systems provide quantitative expression of fluorescence intensity, allowing the introduction of objective quality control procedures to the monitoring of the entire process. The calibration of the reading systems and the automated image interpretation are essential prerequisites for obtaining reproducible and harmonized IIF test results and form the basis for standardization, regardless of the computer algorithms used in the different systems. The use of automated CAD systems, facilitating control procedures, represents a step forward for the quality certification of the laboratory.

Integrating quality assurance in autoimmunity: the changing face of the automated ANA IIF test

OBJECTIVES

Currently available computer-aided diagnosis (CAD) systems for the detection of anti-nuclear antibodies (ANA) by indirect immunofluorescence (IIF) assay enable a standardized measurement of system-specific fluorescent intensity (FI) measures. We aimed to evaluate an internal quality control (iQC) program that controls the total ANA IIF process in routine practice.

METHODS

In addition to the kit iQC materials, supplemental quality indicators were integrated in a total quality assurance (QA) program: patient-derived iQC's samples (negative, 1/160 fine speckled and 1/160 homogeneous), median sample FI per run and percentage of ANA IIF positive samples per run. Analytical rejection criteria were based on the imprecision of the positivity index (PI) measure of the Zenit PRO system (Menarini). Clinical rejection criteria were based on changes in FI that correspond to a change in ANA IIF titer of ≥2. To evaluate the QA program, different artificial errors were introduced during the ANA IIF process. After every run, quality indicators were evaluated and compared to the pre-set target values.

RESULTS

Rescanning the ANA IIF slides five times, using an old conjugate and a needle obstruction resulted in analytically and even clinically relevant errors in ANA IIF results. All errors were correctly detected by the different defined quality indicators. Traditional Westgard rules, including analytically (and clinically) defined rejection limits were useful in monitoring quality indicators.

CONCLUSIONS

The integration of a total process iQC program in CAD systems, based on the specific FI measurands and performance criteria of the system, adds value to QA.

Update of the simplified criteria for autoimmune hepatitis: Evaluation of the methodology for immunoserological testing

BACKGROUND & AIMS

The simplified criteria for the diagnosis of autoimmune hepatitis (AIH) include immunofluorescence testing (IFT) of antinuclear and smooth muscle autoantibodies (ANA and SMA) on rodent tissue sections. We aimed to establish scoring criteria for the implementation of ANA IFT on human epithelioma-2 (HEp-2) cells and ELISA-based testing.

METHODS

ANA and SMA reactivity of 61 AIH sera and 72 non-alcoholic fatty liver disease controls were separately assessed on tissue sections and HEp-2 cells to compare the diagnostic value at increasing titers. A total of 113 patients with AIH at diagnosis and 202 controls from 3 European centers were assessed by IFT as well as 3 different commercially available ANA ELISA and 1 anti-F-actin ELISA.

RESULTS

ANA assessment by IFT on liver sections had 83.6% sensitivity and 69.4% specificity for AIH at a titer of 1:40. On HEp-2 cells, sensitivity and specificity were 75.4% and 73.6%, respectively, at an adjusted titer of 1:160. Area under the curve (AUC) values of ANA ELISA ranged from 0.70-0.87, with ELISA coated with HEp-2 extracts in addition to selected antigens performing significantly better. SMA assessment by IFT had the highest specificity for the SMA-VG/T pattern and anti-microfilament reactivity on HEp-2 cells. ELISA-based anti-F-actin evaluation was a strong predictor of AIH (AUC 0.88) and performed better than SMA assessment by IFT (AUC 0.77-0.87).

CONCLUSION

At adjusted cut-offs, both ANA IFT using HEp-2 cells and ELISA-based autoantibody evaluation for ANA and SMA are potential alternatives to tissue-based IFT for the diagnosis of AIH.

LAY SUMMARY

Autoantibodies are a hallmark of autoimmune hepatitis and are traditionally tested for by immunofluorescence assays on rodent tissue sections. Herein, we demonstrate that human epithelioma cells can be used as a reliable substrate for immunofluorescence testing. ELISA-based testing is also a potentially reliable alternative for autoantibody assessment in autoimmune hepatitis. We propose the implementation of these testing methods into the simplified criteria for the diagnosis of autoimmune hepatitis.

Value of biopsy in a cohort of children with high-titer celiac serologies: observation of dynamic policy differences between Europe and North America

Background

Healthcare systems implement change at different rates because of differences in incentives, organizational processes, key influencers, and management styles. A comparable set of forces may play out at the national and international levels as demonstrated in significant differences in the diagnostic management of pediatric Celiac Disease (CD) between European and North American practitioners.

Methods

We use retrospective clinical cohorts of 27,868 serum tissue transglutaminase (tTG) immunoglobulin A levels and 7907 upper gastrointestinal endoscopy pathology reports to create a dataset of 793 pathology reports with matching tTG results between July 1 of 2014 and July 1 of 2018. We use this dataset to characterize histopathological findings in the duodenum, stomach and esophagus of patients as a function of serum tTG levels. In addition, we use the dataset to estimate the local and national cost of endoscopies performed in patients with serum tTG levels greater than 10 times the upper limit of normal.

Results

Using evidence from a US tertiary care center, we show that in the cohort of pediatric patients with high pre-test probability of CD as determined by serum tTG levels, biopsy provides no additional diagnostic value for CD, and that it counter-intuitively introduces diagnostic uncertainty in a number of patients. We estimate that using the European diagnostic algorithms could avoid between 4891 and 7738 pediatric endoscopies per year in the US for evaluation of CD.

Conclusions

This study considers the North American and European management guidelines for the diagnosis of pediatric CD and highlights the slow adoption in North America of evidence-based algorithms developed and applied in Europe for triage of endoscopy and biopsy. We suggest that system dynamics influences that help maintain the status quo in North America include a variety of social and economic factors in addition to medical evidence. This work contributes to the growing body of evidence that the dynamics that largely favor maintaining status quo management policies in a variety of systems extend to clinical medicine and potentially influence clinical decisions at the level of individual patients and the population.

Supplementary information

Supplementary information accompanies this paper at 10.1186/s12913-020-05815-0.

A new diagnostic algorithm for pattern-oriented autoantibody testing according to the ICAP nomenclature: A pilot study

The commercial tests currently available as second-level tests to detect ANA sub-specificities are generally used independently from the ANA immunofluorescence (IIF) pattern. The aim of this study was to evaluate the efficacy of the use of a customizable pattern-oriented antigenic panel by immunoblot (IB) using the International Consensus on ANA Patterns (ICAP) classification scheme, in order to introduce a novel and updated autoimmune diagnostic flowchart. 710 sera referred for routine ANA testing were selected on the basis of the ANA pattern according to the ICAP nomenclature (nuclear speckled AC-2,4,5; nucleolar AC-8,9,10,29; cytoplasmic speckled AC-18,19,20) and on an IIF titer ≥1:320. They were then assayed by three experimental IB assays using a panel of selected antigens. ICAP-oriented IB detected 515 antibody reactivities vs. 457 of traditional anti-ENA in the nuclear speckled pattern group, 108 vs. 28 in the nucleolar pattern group, and 43 vs. 34 in the cytoplasmic speckled pattern. This pilot study may lead the way for a new approach introducing an ICAP pattern-oriented follow up testing as a valid alternative to the existing standard panels, thus enabling more patients with autoimmune rheumatic disease to be accurately diagnosed.

Receptor autoimmunity: diagnostic and therapeutic implications

Receptor autoimmunity is one of the ways in which autoimmune diseases appear in humans. Graves' disease, myasthenia gravis, idiopathic membranous nephropathy, and autoimmune acute encephalitis are the major autoimmune diseases belonging to this particular group. Receptor autoimmune disease are dependent on the presence of autoantibodies directed against cell-surface antigens, namely TSH receptor in thyrocytes, acetylcholine receptor in neuromuscular junction, phospholipase 2 receptor in podocytes, and NMDA receptor in cortical neurons. In this article we outline the distinctive features of receptor autoimmunity and the specific relationship between the autoimmunology laboratory and the presence/concentration of autoantibodies. Some immunological features distinguish receptor autoimmunity. Anti-receptor autoantibody pathologies are considered T cell-dependent, B-cell-mediated autoimmune disorders: the knowledge about the presence of circulating and/or localized autoantibodies to target organs and identification of autoantigens involved in the autoimmune reaction is of paramount importance. Due to the close correlation between the concentration of anti-receptor autoantibodies, the autoimmune target of some cell-surface receptors and the intensity of symptoms, the measurement of these immunoglobulins has become central to diagnose autoimmune diseases in all affected patients, not just in clinically dubious cases. The measurement of autoantibodies is also relevant for differential diagnosis of autoimmune and non-autoimmune forms with similar symptoms. From the methodological point of view, quantitative immunoassay methods of measurement should be preferred over semi-quantitative ones, for the capacity of the first class of methods to define precisely the reference ranges and decision levels overcoming the measurement uncertainty of semi-quantitative methods.

Thyroid Peroxidase Revisited - What's New?

Thyroid peroxidase (TPO) is an enzyme that participates in thyroid hormone biosynthesis. TPO is also a major autoantigen in autoimmune thyroid diseases (AITD). In this review, we summarize the latest developments in the field of TPO research. We present the current understanding of immunodominant serologic determinants, frequency of TPO-specific autoantibodies in the population, as well as genetic and environmental factors contributing to their development. Moreover, we report recent progress in the clinical utilities of TPO autoantibody testing, including thyroid dysfunctions and extra-thyroidal disorders.

Recurrence of disease following organ transplantation in autoimmune liver disease and systemic lupus erythematosus

Disease recurrence after organ transplantation associated with graft failure is a major clinical challenge in autoimmune diseases. Primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC) and autoimmune Hepatitis (AIH) are the three most common (autoimmune liver diseases) ALD for which liver transplantation (LT) is the most effective treatment option for patients with end-stage diseases. Although the 5- and 10-year survival rates of post-LT patients are remarkable (80-84% and 71-79% in PBC, 73-87% and 58-83% in PSC, 76-79% and 67-77% respectively in AIH patients), post-LT disease recurrence is not uncommon. Here, we summarize literature findings on disease recurrence of these ALD with emphasis on the incidence, risk factors and impact on long-term outcome. We noted that the incidence of disease recurrence varies between studies, which ranges from 53% to 10.9% in PBC, 8.2% to 44.7% in PSC and 7% to 42% in AIH. The variations are likely due to differences in study design, such as sample size, duration of studies and follow up time. This is further compounded by the lack of precise clinical diagnosis criteria and biomarkers of disease recurrence in these ALD, variation in post-LT treatment protocols to prevent disease recurrence and a multitude of risk factors associated with these ALD. While recurrence of PBC and AIH does not significantly impact long term outcome including overall survival, recurrent PSC patients often require another LT. Renal transplantation, like LT, is the treatment of choice in patients with end-stage lupus nephritis. While calcineurin inhibitor (CNI) and immunosuppressive drugs have improved the survival rate, post-transplant recurrence of lupus nephritis from surveillance-biopsy proven lupus nephritis range from 30% to 44%. On the other hand, recurrence of post-transplant lupus nephritis from registry survey analysis were only 1.1% to 2.4%. In general, risk factors associated with an increased frequency of post-transplant recurrence of autoimmune diseases are not clearly defined. Large scale multi-center studies are needed to further define guidelines for the diagnosis and clinical management to minimize disease recurrence and improve outcomes of post-transplant patients.

A cross-reactive monoclonal antibody as universal detection antibody in autoantibody diagnostic assays

Diagnostics of Autoimmune Diseases involve screening of patient samples for containing autoantibodies against various antigens. To ensure quality of diagnostic assays a calibrator is needed in each assay system. Different calibrators as recombinant human monoclonal antibodies as well as chimeric antibodies against the autoantigens of interest are described. A less cost-intensive and also more representative possibility covering different targets on the antigens is the utilization of polyclonal sera from other species. Nevertheless, the detection of human autoantibodies as well as the calibration reagent containing antibodies from other species in one assay constitutes a challenge in terms of assay calibration. We therefore developed a cross-reactive monoclonal antibody which binds human as well as rabbit sera with similar affinities in the nanomolar range. We tested our monoclonal antibody S38CD11B12 successfully in the commercial Serazym® Anti-Cardiolipin-ß2-GPI IgG/IgM assay and could thereby prove the eligibility of S38CD11B12 as detection antibody in autoimmune diagnostic assays using rabbit derived sera as reference material.

Autoantibody Profiles in Autoimmune Rheumatic Diseases

A paradigmatic feature of autoimmune rheumatic diseases (ARD) is the presence of multiple autoantibodies. The use of antibody profiles in the study of ARD therefore should be the best strategy for both diagnostic and classification purposes. To this end, systems using micronized components (protein chips or arrays), consisting of solid phase-linked autoantigens capable of simultaneously detecting many autoantibodies at the same time, are particularly suitable for testing autoantibody profiles. In the near future, extended disease-specific autoantibody profiles consisting of dozens, if not hundreds, of autoantibodies will be able to define each patient's autoantibody fingerprint and identify subclasses of patients with different prognostic characteristics and different therapeutic responses.

Review article: unanswered clinical and research questions in autoimmune hepatitis-conclusions of the International Autoimmune Hepatitis Group Research Workshop

BACKGROUND

Autoimmune hepatitis (AIH) is a chronic inflammatory liver disease that results in substantial morbidity and mortality with many unanswered clinical and research questions. Improved understanding of disease pathogenesis, including the extra-hepatic manifestations of AIH, may allow targeted treatments with greater efficacy and fewer associated adverse events.

AIM

To identify the spectrum of unanswered clinical and research questions facing care providers in the management of patients with autoimmune hepatitis (AIH).

METHODS

The International Autoimmune Hepatitis Group initiated a series of research workshops to start to address these questions. Key issues were discussed in small group sessions with collation of all discussions to be summarised in this manuscript.

RESULTS

Key issues were identified as: the need for better understanding of disease pathogenesis, standardisation of the methods and assays used to evaluate autoantibodies in AIH, refinement of the histopathological criteria for "typical" or "compatible" AIH, focus on the interaction with non-alcohol related fatty liver disease, how to treat acute severe AIH, better assessment of quality of life in adults and paediatrics, standardising use of standard, third-line and experimental therapies in AIH and search for biomarkers early in the disease course that predict outcome.

CONCLUSION

This workshop has outlined the key unanswered clinical and research questions to help to define the research agenda in AIH.

Harmonizing by reducing inter-run variability: performance evaluation of a quality assurance program for antinuclear antibody detection by indirect immunofluorescence

Background

The introduction of automated anti-nuclear antibody (ANA) indirect immunofluorescence (IIF) analysis may allow for more harmonized ANA IIF reporting, provided that a thorough quality assurance program controls this process. The aim of this study was to evaluate various quality indicators used for ANA IIF analysis with the final goal of optimizing the iQC program.

Methods

In an experimental setup, we introduced artificial errors, mimicking plausible problems during routine practice on a QUANTA-Lyser-NOVA View® system (Inova Diagnostics, San Diego, CA, USA). Predetermined quality indicators were evaluated against predefined acceptance criteria. In addition, we retrospectively investigated the applicability of the selected quality indicators in the daily routine practice during three pre-defined periods.

Results

Both the experimental as the retrospective study revealed that pre-analytical, analytical and post-analytical errors were not highlighted by company internal quality control (iQC) materials. The use of patient derived iQC samples, median fluorescence intensity results per run and the percentage of positive ANA IIF results as additional quality indicators ensured a more adequate ANA IIF quality assurance. Furthermore, negative and moderate positive sample iQC materials merit clinical validation, as titer changes of >1 correspond to clinically important shifts. Traditional Westgard rules, including a clinically defined stop limit, revealed to be useful in monitoring of the supplemental quality indicators.

Conclusions

A thorough ANA IIF quality assurance for daily routine practice necessitates the addition of supplemental quality indicators in combination with well-defined acceptance criteria.

Standardization of Autoantibody Testing in Autoimmune Hepatitis

It is a comment on a recent review published on the Journal.

Harmonization in laboratory medicine: more than clinical chemistry?

The goal of harmonizing laboratory information is to contribute to quality in patient care, ultimately improving upon patient outcomes and safety. The main focus of harmonization and standardization initiatives has been on analytical processes within the laboratory walls, clinical chemistry tests in particular. However, two major evidences obtained in recent years show that harmonization should be promoted not only in the analytical phase but also in all steps of the testing process, encompassing the entire field of laboratory medicine, including innovative areas (e.g. “omics”) rather than just conventional clinical chemistry tests. A large body of evidence demonstrates the vulnerability of the extra-analytical phases of the testing cycle. Because only “good biological samples” can assure good analytical quality, a closer interconnection between the different phases of the cycle is needed. In order to provide reliable and accurate laboratory information, harmonization activities should cover all steps of the cycle from the “pre-pre-analytical” phase (right choice of test at right time for right patient) through the analytical steps (right results with right report) to the “post-post-analytical” steps (right and timely acknowledgment of laboratory information, right interpretation and utilization with any necessary advice as to what to do next with the information provided). In addition, modern clinical laboratories are performing a broad menu of hundreds of tests, covering both traditional and innovative subspecialties of the discipline. In addition, according to a centered viewpoint, harmonization initiatives should not be addressed exclusively to clinical chemistry tests but should also include all areas of laboratory medicine.

The Clinical Significance of GP73 in Immunologically Mediated Chronic Liver Diseases: Experimental Data and Literature Review

There is significant void in establishing validated non-invasive surrogate biomarkers of liver fibrosis/cirrhosis in chronic liver diseases (CLD). Golgi protein 73 (GP73) has been suggested as a potential serum marker for the diagnosis of hepatocellular carcinoma (HCC). However, significant background of cirrhosis could have accounted for the elevation of serum GP73 in HCC. In this study, we have taken advantage of a well-defined extensive cohort of 3044 patients with either compensated cirrhosis (n = 1247), decompensated cirrhosis (n = 841) or pre-cirrhotic CLD (n = 956) and our ability to quantify serum GP73 to define the potential of serum GP73 as a biomarker of liver cirrhosis/fibrosis in CLD. The diagnostic value of GP73 was compared with aspartate aminotransferase-to-platelet ratio index (APRI), fibrosis index based on four factors (FIB-4) and liver stiffness measurement (LSM). Immunohistochemical analysis was performed to measure hepatic GP73 expression. Receiver operating characteristic curve analysis demonstrated that serum GP73 had a good diagnostic potential for compensated cirrhosis regardless of etiology. The diagnostic performance of GP73 is better than APRI, FIB-4 and similar with LSM, especially in patients with severe inflammation, steatosis and cholestasis. Notably, in patients of autoimmune liver diseases, non-alcoholic fatty liver disease and viral hepatitis, serum GP73 also exhibited diagnostic value for advanced fibrosis as well as cirrhosis. Furthermore, there is also a gradual increase in GP73 expression with disease progression from mild fibrosis to cirrhosis. In conclusion, GP73 is an effective and reliable serological marker for the diagnosis of advanced fibrosis and prediction of appearance of cirrhosis.

Harmonization in autoimmune thyroid disease diagnostics

In this review we analyze all aspects of total testing process regarding the measurement of antithyroid peroxidase, antithyroglobulin and antithyrotropin receptor autoantibodies. The main critical points related to the preanalytical, analytical and postanalytical steps of autoimmune thyroid disease diagnostics are considered, focusing on harmonization of autoimmune thyroid tests request, retesting intervals, terminology of thyroid autoantibodies, measurement units and definition of reference limits. Harmonization in thyroid autoantibody testing is a relevant example of feasible harmonization in autoimmunology.

Bench to bedside review of myositis autoantibodies

Idiopathic inflammatory myopathies represent a heterogeneous group of autoimmune diseases with systemic involvement. Even though numerous specific autoantibodies have been recognized, they have not been included, with the only exception of anti-Jo-1, into the 2017 Classification Criteria, thus perpetuating a clinical-serologic gap. The lack of homogeneous grouping based on the antibody profile deeply impacts the diagnostic approach, therapeutic choices and prognostic stratification of these patients. This review is intended to highlight the comprehensive scenario regarding myositis-related autoantibodies, from the molecular characterization and biological significance to target antigens, from the detection tools, with a special focus on immunofluorescence patterns on HEp-2 cells, to their relative prevalence and ethnic diversity, from the clinical presentation to prognosis. If, on the one hand, a notable body of literature is present, on the other data are fragmented, retrospectively based and collected from small case series, so that they do not sufficiently support the decision-making process (i.e. therapeutic approach) into the clinics.

Autoimmune hepatitis - update on clinical management in 2017

Autoimmune hepatitis (AIH) is a progressive immune mediated liver disease of unknown origin. Key diagnostic features include hypergammaglobulinemia/elevated serum-IgG, characteristic circulating autoantibodies, periportal hepatitis with interface activity on liver biopsy and the exclusion of hepatotropic viruses. However, the diagnosis is challenging in cholestatic and severe presentations. It can be difficult to differentiate AIH from drug-induced liver injury. Although many patients initially respond to standard immunosuppressive therapy, a significant proportion experiences intolerable side effects or insufficient treatment response. This underlines the need for effective alternative treatment options, which are still very limited and based on rather poor evidence. This review summarises core aspects of the clinical management of AIH with focus on recent achievements and unmet needs.

Chronic Autoimmune Epithelitis in Sjögren's Syndrome and Primary Biliary Cholangitis: A Comprehensive Review

Within the spectrum of autoimmune diseases, Sjögren's syndrome and primary biliary cholangitis are exemplary and can be coined as chronic epithelitis based on their frequent coexistence in clinical practice and the highly specific immune-mediated injury of the small bile ducts and the exocrine glands. The pathogenic mechanisms underlying the diseases are similar, with apoptosis being the key element leading to organ-specific immune-mediated injury directed against the small bile ducts and salivary gland epithelia, respectively along with similar epidemiological features, such as female predominance and the age of onset in the fifth decade of life. Indeed, novel insights into the pathogenesis of the diseases have been obtained in recent years, including a better definition of the role of B and T cells, particularly Th17 cells, and the mechanisms of autoantibody-mediated tissue injury, with anti-mitochondrial antibodies and SS-A/SS-B being identified as specific for primary biliary cholangitis and Sjögren's syndrome, respectively. These findings have opened the possibility to new targeted therapies, but most clinical needs remain unmet, particularly from a therapeutic standpoint where options diverge, with bile acids being the predominant treatment strategy in primary biliary cholangitis and immunomodulators being used to treat Sjögren's syndrome. Here we provide a comprehensive review of the most recent findings on the pathogenesis, clinical manifestations and therapeutic options for Sjögren's syndrome and primary biliary cholangitis, respectively, while stressing the common traits between these conditions. Our cumulative hypothesis is that similarities outnumber differences and that this may prove advantageous towards a better management of patients.

Personalized medicine in rheumatology: the paradigm of serum autoantibodies

The sequencing of the human genome is now well recognized as the starting point of personalized medicine. Nonetheless, everyone is unique and can develop different phenotypes of the same disease, despite identical genotypes, as well illustrated by discordant monozygotic twins. To recognize these differences, one of the easiest and most familiar examples of biomarkers capable of identifying and predicting the outcome of patients is represented by serum autoantibodies. In this review, we will describe the concept of personalized medicine and discuss the predictive, prognostic and preventive role of antinuclear antibodies (ANA), anti-citrullinated peptide antibodies (ACPA), rare autoantibodies and anti-drug antibodies (ADA), to evaluate how these can help to identify different disease immune phenotypes and to choose the best option for treating and monitoring rheumatic patients in everyday practice. The importance of ANA resides in the prediction of clinical manifestations in systemic sclerosis and systemic lupus erythematosus and their association with malignancies. ACPA have a predictive role in rheumatoid arthritis, they are associated with the development of a more aggressive disease, extra-articular manifestations and premature mortality in RA patients; moreover, they are capable of predicting therapeutic response. Rare autoantibodies are associated with different disease manifestations and also with a greater incidence of cancer. The determination of ADA levels may be useful in patients where the clinical efficacy of TNF-α inhibitor has dropped, for the assessment of a right management. The resulting scenario supports serum autoantibodies as the cornerstone of personalized medicine in autoimmune diseases.