Evidence-based guidelines for the use of immunologic tests: antinuclear antibody testing

Current state of diagnostic technologies in the autoimmunology laboratory

The methods for detecting and measuring autoantibodies have evolved markedly in recent years, encompassing three generations of analytical technologies. Many different immunoassay methods have been developed and used for research and laboratory practice purposes, from the early conventional (or monoplex) analytical methods able to detect single autoantibodies to the more recent multiplex platforms that can quantify tens of molecules. Although it has been in use for over 50 years, indirect immunofluorescence remains the standard method for research on many types of autoantibodies, due to its characteristics of diagnostic sensitivity and also to recent technological innovations which permit it a greater level of automation and standardization. The recent multiplex immunometric methods, with varying levels of automation, present characteristics of higher diagnostic accuracy, but are not yet widely diffused in autoimmunology laboratories due to the limited number of autoantibodies that are detectable, and due to the high cost of reagents and systems. Technological advancement in autoimmunology continues to evolve rapidly, and in the coming years new proteomic techniques will be able to radically change the approach to diagnostics and possibly also clinical treatment of autoimmune diseases. The scope of this review is to update the state of the art of technologies and methods for the measurement of autoantibodies, with special reference to innovations in indirect immunofluorescence and in multiple proteomic methods.

Anti-nuclear antibodies in daily clinical practice: prevalence in primary, secondary, and tertiary care

For the diagnosis of systemic autoimmune rheumatic diseases (SARD), patients are screened for anti-nuclear antibodies (ANA). ANA, as assessed by indirect immunofluorescence (IIF), have a poor specificity. This hampers interpretation of positive results in clinical settings with low pretest probability of SARD. We hypothesized that the utility of positive ANA IIF results increases from primary to tertiary care. We retrospectively determined ANA, anti-ENA, and anti-dsDNA antibody prevalence in patient cohorts from primary (n = 1453), secondary (n = 1621), and tertiary (n = 1168) care settings. Results reveal that from primary care to tertiary care, ANA prevalence increases (6.2, 10.8, and 16.0%, resp.). Moreover, in primary care low titres (70% versus 51% and 52% in secondary and tertiary care, resp.) are more frequent and anti-ENA/dsDNA reactivities are less prevalent (21% versus 39% in secondary care). Typically, in tertiary care the prevalence of anti-ENA/dsDNA reactivities (21%) is lower than expected. From this descriptive study we conclude that positive ANA IIF results are more prone to false interpretation in clinical settings with low pretest probabilities for SARD, as in primary care. Whether alternative approaches, that is, immunoadsorption of anti-DFS70 antibodies or implementation of anti-ENA screen assays, perform better, needs to be determined.

Automated tests of ANA immunofluorescence as throughput autoantibody detection technology: strengths and limitations

Anti-nuclear antibody (ANA) assay is a screening test used for almost all autoimmune rheumatic diseases, and in a number of these cases, it is a diagnostic/classification parameter. In addition, ANA is also a useful test for additional autoimmune disorders. The indirect immunofluorescence technique on monolayers of cultured epithelial cells is the current recommended method because it has higher sensitivity than solid phase assays. However, the technique is time-consuming and requires skilled operators. Automated ANA reading systems have recently been developed, which offer the advantage of faster and much easier performance as well as better harmonization in the interpretation of the results. Preliminary validation studies of these systems have given promising results in terms of analytical specificity and reproducibility. However, these techniques require further validation in clinical studies and need improvement in their recognition of mixed or less common staining patterns.

High prevalence of antinuclear antibodies in children with thyroid autoimmunity

BACKGROUND

Antinuclear antibodies (ANA) are a hallmark of many autoimmune diseases and can be detected many years before disease onset. Autoimmune thyroid diseases (AITD) are frequently associated with other organ- and non-organ-specific autoimmune disorders. Objectives. To assess the prevalence of ANA in pediatric patients with AITD and their clinical correlations.

METHODS

Ninety-three consecutive pediatric patients with AITD were enrolled (86 children with chronic lymphocytic thyroiditis and 7 with Graves' disease). ANA, anti-double DNA (anti-dsDNA) antibodies, anti-extractable nuclear antigen (anti-ENA), anti-cyclic citrullinated peptide antibodies (anti-CCP), and rheumatoid factor (RF) was obtained. Signs and symptoms potentially related to rheumatic diseases in children were investigated by a questionnaire.

RESULTS

ANA positivity was found in 66/93 children (71%), anti-ENA in 4/93 (4.3%), anti-dsDNA in 1/93 (1.1%), RF in 3/93 (3.2%), and anti-CCP in none. No significant differences were found between the ANA-positive and ANA-negative groups with respect to age, sex, L-thyroxine treatment, or prevalence of other autoimmune diseases. Overall, parental autoimmunity was found in 23%.

CONCLUSIONS

ANA positivity was demonstrated in 71% of children with AITD. ANA positivity was not related to overt immune-rheumatic diseases. However, because the positivity of ANA can occur even many years before the onset of systemic autoimmune diseases, prospective studies are warranted.

Utility of immunologic testing in suspected rheumatologic disease

The use of diagnostic testing in the clinical practice of medicine has been a shifting landscape from the time that the first blood test was utilized. This is no different in the field of immunology and in particular rheumatology. As the field of immunology is relatively young, the clinical tests are not well established and therefore guidelines for use are still under debate. In this review, we seek to look at some of the key autoantibodies, as well as other tests that are available to diagnose suspected rheumatologic disease, and examine how to best use these tests in the clinic. In particular, we will focus on the anti-nuclear antibodies, anti-neutrophil cytoplasmic antibodies, complement, cryoglobulins, rheumatoid factor, and anti-citrullinated protein antibodies.

Serology of Lupus Erythematosus: Correlation between Immunopathological Features and Clinical Aspects

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the aberrant production of a broad and heterogenous group of autoantibodies. Even though the presence of autoantibodies in SLE has been known, for more than 60 years, still nowadays a great effort is being made to understand the pathogenetic, diagnostic, and prognostic meaning of such autoantibodies. Antibodies to ds-DNA are useful for the diagnosis of SLE, to monitor the disease activity, and correlate with renal and central nervous involvements. Anti-Sm antibodies are highly specific for SLE. Anti-nucleosome antibodies are an excellent marker for SLE and good predictors of flares in quiescent lupus. Anti-histone antibodies characterize drug-induced lupus, while anti-SSA/Ro and anti-SSB/La antibodies are associated with neonatal lupus erythematosus and photosensitivity. Anti-ribosomal P antibodies play a role in neuropsychiatric lupus, but their association with clinical manifestations is still unclear. Anti-phospholipid antibodies are associated with the anti-phospholipid syndrome, cerebral vascular disease, and neuropsychiatric lupus. Anti-C1q antibodies amplify glomerular injury, and the elevation of their titers may predict renal flares. Anti-RNP antibodies are a marker of Sharp's syndrome but can be found in SLE as well. Anti-PCNA antibodies are present in 5–10% of SLE patients especially those with arthritis and hypocomplementemia.

Fitting and flailing: recognition of paediatric antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a systemic autoimmune condition where the presence of antiphospholipid antibodies is thought to predispose to thrombotic events. It is uncommon in the paediatric population, but current diagnostic criteria are based on adult population studies, making assessment of its true paediatric prevalence difficult. We present two cases of paediatric APS, who presented with primary neurological events, and discuss approaches to diagnosis, interpretation of screening investigations, including antinuclear antibodies (ANA), anti-extractable nuclear antigen (ENA) antibodies and lupus anticoagulant. Possible approaches to the management of paediatric APS are discussed.

A comparison of anti-nuclear antibody quantification using automated enzyme immunoassays and immunofluorescence assays

Anti-nuclear antibodies (ANA) have traditionally been evaluated using indirect fluorescence assays (IFA) with HEp-2 cells. Quantitative immunoassays (EIA) have replaced the use of HEp-2 cells in some laboratories. Here, we evaluated ANA in 400 consecutive and unselected routinely referred patients using IFA and automated EIA techniques. The IFA results generated by two independent laboratories were compared with the EIA results from antibodies against double-stranded DNA (dsDNA), from ANA screening, and from tests of the seven included subantigens. The final IFA and EIA results for 386 unique patients were compared. The majority of the results were the same between the two methods (n = 325, 84%); however, 8% (n = 30) yielded equivocal results (equivocal-negative and equivocal-positive) and 8% (n = 31) yielded divergent results (positive-negative). The results showed fairly good agreement, with Cohen's kappa value of 0.30 (95% confidence interval (CI) = 0.14–0.46), which decreased to 0.23 (95% CI = 0.06–0.40) when the results for dsDNA were omitted. The EIA method was less reliable for assessing nuclear and speckled reactivity patterns, whereas the IFA method presented difficulties detecting dsDNA and Ro activity. The automated EIA method was performed in a similar way to the conventional IFA method using HEp-2 cells; thus, automated EIA may be used as a screening test.

Evaluation of an automated chemiluminescent immunoassay kit for antinuclear antibodies in autoimmune diseases

The identification of antinuclear antibodies (ANA) is an essential step in the diagnosis of different autoimmune diseases. The gold standard method for their detection is immunofluorescence assay. However, this is a subjective and laborious method, thus a need for simplified objective methods has aroused. In the current work, we evaluated such automated method, the LIAISON(®) (DiaSorin, Italy) for the detection of ANA. A total of 242 sera were analyzed including 67 from healthy subjects, 107 from primary biliary cirrhosis (PBC) patients, 20 from scleroderma patients and 48 from patients with Sjögren's syndrome. All sera were analyzed using the automated chemiluminescent immunoassays, LIAISON(®) for the presence of ANA (kit No. 310300). Positive samples were further analyzed for the presence of antidouble-stranded DNA (dsDNA) and autoantibodies to 6 extractable nuclear antigens (ENA) of the LIAISON(®) (kits No. 310330 and 310331). Negative samples were further analyzed by Blueblot ANA assay (D-TEK, Belgium) or BlueDot Liver (D-TEK, Belgium) as appropriate. The LIAISON(®) specificity for ANA screening was 97%. ANA positivity was determined in 80% of all patients. The sensitivity was 95.5% in scleroderma, 83% in PBC and 72.9% in Sjogren's syndrome. ENA was positive in all ANA-positive scleroderma and Sjögren's sera and in 27% of ANA-positive PBC sera. Among scleroderma or Sjögren patients that were ANA negative, 4 samples were positive for anti-SSA and 2 for RNP-68 utilizing Blueblot assays. M2 protein was found in 1 out of the ANA-negative PBC patients. The LIAISON(®) ANA screen is specific and sensitive for the evaluation of ANA in patients with primary biliary cirrhosis, scleroderma and Sjögren's syndrome.

Novel method for ANA quantitation using IIF imaging system

A variety of antinuclear antibodies (ANAs) are found in the serum of patients with autoimmune diseases. The detection of abnormal ANA titers is a critical criterion for diagnosis of systemic lupus erythematosus (SLE) and other connective tissue diseases. Indirect immunofluorescence assay (IIF) on HEp-2 cells is the gold standard method to determine the presence of ANA and therefore provides information about the localization of autoantigens that are useful for diagnosis. However, its utility was limited in prognosing and monitoring of disease activity due to the lack of standardization in performing the technique, subjectivity in interpreting the results and the fact that it is only semi-quantitative. On the other hand, ELISA for the detection of ANA can quantitate ANA but could not provide further information about the localization of the autoantigens. It would be ideal to integrate both of the quantitative and qualitative methods. To address this issue, this study was conducted to quantitatively detect ANAs by using IIF imaging analysis system. Serum samples from patients with ANA positive (including speckled, homogeneous, nuclear mixture and cytoplasmic mixture patterns) and negative were detected for ANA titers by the classical IIF and analyzed by an image system, the image of each sample was acquired by the digital imaging system and the green fluorescence intensity was quantified by the Image-Pro plus software. A good correlation was found in between two methods and the correlation coefficients (R(2)) of various ANA patterns were 0.942 (speckled), 0.942 (homogeneous), 0.923 (nuclear mixture) and 0.760 (cytoplasmic mixture), respectively. The fluorescence density was linearly correlated with the log of ANA titers in various ANA patterns (R(2)>0.95). Moreover, the novel ANA quantitation method showed good reproducibility (F=0.091, p>0.05) with mean±SD and CV% of positive, and negative quality controls were equal to 126.4±9.6 and 7.6%, 10.4±1.25 and 12.0%, respectively. In conclusion, our novel ANA quantitation method can provide both of the fluorescence density, which could precisely reflect the fluctuate of ANAs level in patient's serum and the useful information about the localization of the autoantigens for clinician in diagnosing and monitoring diseases.

Original approach for automated quantification of antinuclear autoantibodies by indirect immunofluorescence

Introduction. Indirect immunofluorescence (IIF) is the gold standard method for the detection of antinuclear antibodies (ANA) which are essential markers for the diagnosis of systemic autoimmune rheumatic diseases. For the discrimination of positive and negative samples, we propose here an original approach named Immunofluorescence for Computed Antinuclear antibody Rational Evaluation (ICARE) based on the calculation of a fluorescence index (FI). Methods. We made comparison between FI and visual evaluations on 237 consecutive samples and on a cohort of 25 patients with SLE. Results. We obtained very good technical performance of FI (95% sensitivity, 98% specificity, and a kappa of 0.92), even in a subgroup of weakly positive samples. A significant correlation between quantification of FI and IIF ANA titers was found (Spearman's ρ = 0.80, P < 0.0001). Clinical performance of ICARE was validated on a cohort of patients with SLE corroborating the fact that FI could represent an attractive alternative for the evaluation of antibody titer. Conclusion. Our results represent a major step for automated quantification of IIF ANA, opening attractive perspectives such as rapid sample screening and laboratory standardization.

Standardization of autoantibody testing: a paradigm for serology in rheumatic diseases

Autoantibody measurement is an excellent tool to confirm the diagnosis of rheumatic autoimmune diseases. Hence, reliability and harmonization of autoantibody testing are essential, but these issues are still a matter of debate. Intrinsic variability in analytes and reagents as well as heterogeneity of the techniques are the main reasons for discrepancies in inter-laboratory variations and reporting of test results. This lack of reliability might be responsible for wrong or missed diagnoses, as well as additional costs due to assay repetition, unnecessary use of confirmatory tests and/or consequent diagnostic investigations. To overcome such issues, the standardization of autoantibody testing requires efforts on all aspects of the assays, including the definition of the analyte, the pre-analytical stages, the calibration method and the reporting of results. As part of such efforts, the availability of suitable reference materials for calibration and quality control would enable the development of a reliable reference system. Strong-positive sera from patients have been used as reference materials in most of the autoantibody assays for rheumatic diseases; however, antigen-affinity-purified immunoglobulin fractions or in some cases reliable monoclonal antibody preparations offer more adequate tools for standardization. Systematic assessments of reference materials are currently underway, and preliminary results appear to be encouraging.

Discovery of biomarkers for systemic lupus erythematosus using a library of synthetic autoantigen surrogates

Antibodies to a wide range of self-antigens, including those directed against nucleic acids or nucleic acid-binding proteins are the essential biomarkers for diseases such as systemic lupus erythematosus (SLE). Highly complex libraries of nonamers consisting of N-substituted glycines (peptoids) were screened for compounds that bound IgG from patients with SLE and earlier, incomplete autoimmune syndromes. Peptoids were identified that could identify subjects with SLE and related syndromes with a high sensitivity (70%) and specificity (97.5%). Immobilized peptoids were used to isolate IgG from both healthy subjects and SLE patients that reacted with known RNA-binding proteins. In the case of SLE patients, the peptoid-purified IgG reacted with several autoantigens, suggesting that the peptoids are capable of interacting with multiple, structurally similar molecules. These results show that the measurement of IgG binding to peptoids can identify subjects with high levels of pathogenic autoantibodies.

Automated antinuclear immunofluorescence antibody screening: a comparative study of six computer-aided diagnostic systems

BACKGROUND

Indirect immunofluorescence (IIF) plays an important role in immunological assays for detecting and measuring autoantibodies. However, the method is burdened by some unfavorable features: the need for expert morphologists, the subjectivity of interpretation, and a low degree of standardization and automation. Following the recent statement by the American College of Rheumatology that the IIF technique should be considered as the standard screening method for the detection of anti-nuclear antibodies (ANA), the biomedical industry has developed technological solutions which might significantly improve automation of the procedure, not only in the preparation of substrates and slides, but also in microscope reading.

METHODS

We collected 104 ANA-positive sera from patients with a confirmed clinical diagnosis of autoimmune disease and 40 ANA-negative sera from healthy blood donors. One aliquot of each serum, without information about pattern and titer, was sent to six laboratories of our group, where the sera were tested with the IIF manual method provided by each of the six manufacturers of automatic systems. Assignment of result (pos/neg), of pattern and titer was made by consensus at a meeting attended by all members of the research team. Result was assigned if consensus for pos/neg was reached by at least four of six certifiers, while for the pattern and for the titer, the value observed with higher frequency (mode) was adopted. Seventeen ANA-positive sera and six ANA-negative sera were excluded. Therefore, the study with the following automatic instrumentation was conducted on 92 ANA-positive sera and on 34 ANA-negative sera: Aklides, EUROPattern, G-Sight (I-Sight-IFA), Helios, Image Navigator, and Nova View. Analytical imprecision was measured in five aliquots of the same serum, randomly added to the sample series.

RESULTS

Overall sensitivity of the six automated systems was 96.7% and overall specificity was 89.2%. Most false negatives were recorded for cytoplasmic patterns, whereas among nuclear patterns those with a low level of fluorescence (i.e., multiple nuclear dots, midbody, nuclear rim) were sometimes missed. The intensity values of the light signal of various instruments showed a good correlation with the titer obtained by manual reading (Spearman's rho between 0.672 and 0.839; P<0.0001 for all the systems). Imprecision ranged from 1.99% to 25.2% and, for all the systems, it was lower than that obtained by the manual IIF test (39.1%). The accuracy of pattern recognition, which is for now restricted to the most typical patterns (homogeneous, speckled, nucleolar, centromere, multiple nuclear dots and cytoplasmic) was limited, ranging from 52% to 79%.

CONCLUSIONS

This study, which is the first to compare the diagnostic accuracy of six systems for automated ANA-IIF reading on the same series of sera, showed that all systems are able to perform very well the task for which they were created. Indeed, cumulative automatic discrimination between positive and negative samples had 95% accuracy. All the manufacturers are actively continuing the development of new and more sophisticated software for a better definition in automatic recognition of patterns and light signal conversion in end-point titer. In the future, this may avert the need for serum dilution for titration, which will be a great advantage in economic terms and time-saving.

Predictive value of antinuclear antibodies in autoimmune diseases classified by clinical criteria: Analytical study in a specialized health institute, one year follow-up

Introduction: Determination of antinuclear antibodies (ANA) by indirect immunofluorescence (IIF) is usually the initial test for the diagnosis of systemic rheumatic diseases (SRD). Assigning predictive values to positive and negative results of the test is vital because lack of knowledge about ANAs and their usefulness in classification criteria of SRD leads to inappropriate use. Methods: Retrospective study, ANA tests requested by different specialties, correlation to patients' final diagnosis. Results: The prevalence of autoimmune disease was relatively low in our population yielding a low PPV and a high NPV for the ANA test. 40% of the patients had no clinical criteria applied prior to test. Coexistence of two or more autoimmune disorders affects prevalence and predictive values. Conclusion: Application of the test after careful evaluation for clinical criteria remarkably improves the positive likelihood ratio for the diagnosis.

Associations between antinuclear antibody staining patterns and clinical features of systemic lupus erythematosus: analysis of a regional Swedish register

OBJECTIVE

Antinuclear antibody (ANA) analysis by immunofluorescence (IF) microscopy remains a diagnostic hallmark of systemic lupus erythematosus (SLE). The clinical relevance of ANA fine-specificities in SLE has been addressed repeatedly, whereas studies on IF-ANA staining patterns in relation to disease manifestations are very scarce. This study was performed to elucidate whether different staining patterns associate with distinct SLE phenotypes.

DESIGN

Observational cohort study.

SETTING

One university hospital rheumatology unit in Sweden.

PARTICIPANTS

The study population consisted of 222 cases (89% women; 93% Caucasians), where of 178 met ≥4/11 of the 1982 American College of Rheumatology (ACR-82) criteria. The remaining 20% had an SLE diagnosis based on positive IF-ANA (HEp-2 cells) and ≥2 typical organ manifestations at the time of diagnosis (Fries' criteria).

OUTCOME MEASURES

The IF-ANA staining patterns homogenous (H-ANA), speckled (S-ANA), combined homogenous and speckled (HS-ANA), centromeric (C-ANA), nucleolar (N-ANA)±other patterns and other nuclear patterns (oANA) were related to disease manifestations and laboratory measures. Antigen-specificities were also considered regarding double-stranded DNA (Crithidia luciliae) and the following extractable nuclear antigens: Ro/SSA, La/SSB, Smith antigen (Sm), small nuclear RNP (snRNP), Scl-70 and Jo-1 (immunodiffusion and/or line-blot technique).

RESULTS

54% of the patients with SLE displayed H-ANA, 22% S-ANA, 11% HS-ANA, 9% N-ANA, 1% C-ANA, 2% oANA and 1% were never IF-ANA positive. Staining patterns among patients meeting Fries' criteria alone did not differ from those fulfilling ACR-82. H-ANA was significantly associated with the 10th criterion according to ACR-82 ('immunological disorder'). S-ANA was inversely associated with arthritis, 'immunological disorder' and signs of organ damage.

CONCLUSIONS

H-ANA is the dominant IF-ANA pattern among Swedish patients with SLE, and was found to associate with 'immunological disorder' according to ACR-82. The second most common pattern, S-ANA, associated negatively with arthritis and organ damage.

International recommendations for the assessment of autoantibodies to cellular antigens referred to as anti-nuclear antibodies

Anti-nuclear antibodies (ANA) are fundamental for the diagnosis of autoimmune diseases, and have been determined by indirect immunofluorescence assay (IIFA) for decades. As the demand for ANA testing increased, alternative techniques were developed challenging the classic IIFA. These alternative platforms differ in their antigen profiles, sensitivity and specificity, raising uncertainties regarding standardisation and interpretation of incongruent results. Therefore, an international group of experts has created recommendations for ANA testing by different methods. Two groups of experts participated in this initiative. The European autoimmunity standardization initiative representing 15 European countries and the International Union of Immunologic Societies/World Health Organization/Arthritis Foundation/Centers for Disease Control and Prevention autoantibody standardising committee. A three-step process followed by a Delphi exercise with closed voting was applied. Twenty-five recommendations for determining ANA (1-13), anti-double stranded DNA antibodies (14-18), specific antibodies (19-23) and validation of methods (24-25) were created. Significant differences between experts were observed regarding recommendations 24-25 (p<0.03). Here, we formulated recommendations for the assessment and interpretation of ANA and associated antibodies. Notably, the roles of IIFA as a reference method, and the importance of defining nuclear and cytoplasmic staining, were emphasised, while the need to incorporate alternative automated methods was acknowledged. Various approaches to overcome discrepancies between methods were suggested of which an improved bench-to-bedside communication is of the utmost importance. These recommendations are based on current knowledge and can enable harmonisation of local algorithms for testing and evaluation of ANA and related autoantibodies. Last but not least, new more appropriate terminologies have been suggested.

Benchmarking HEp-2 cells classification methods

In this paper, we report on the first edition of the HEp-2 Cells Classification contest, held at the 2012 edition of the International Conference on Pattern Recognition, and focused on indirect immunofluorescence (IIF) image analysis. The IIF methodology is used to detect autoimmune diseases by searching for antibodies in the patient serum but, unfortunately, it is still a subjective method that depends too heavily on the experience and expertise of the physician. This has been the motivation behind the recent initial developments of computer aided diagnosis systems in this field. The contest aimed to bring together researchers interested in the performance evaluation of algorithms for IIF image analysis: 28 different recognition systems able to automatically recognize the staining pattern of cells within IIF images were tested on the same undisclosed dataset. In particular, the dataset takes into account the six staining patterns that occur most frequently in the daily diagnostic practice: centromere, nucleolar, homogeneous, fine speckled, coarse speckled, and cytoplasmic. In the paper, we briefly describe all the submitted methods, analyze the obtained results, and discuss the design choices conditioning the performance of each method.

Carbohydrate antigen 15.3 as a serum biomarker of interstitial lung disease in systemic sclerosis patients

BACKGROUND

To determine the usefulness of Ca 15.3 as a candidate biomarker in systemic sclerosis (SSc) patients with interstitial lung disease (ILD).

METHODS

Two-hundred-twenty-one SSc patients with Ca 15.3 determinations were considered; 168 had evidence of interstitial lung involvement on high-resolution computed tomography (HRCT); digitalized scans were available for scoring in 84 subjects. Discrimination between patients with or without ILD, was assessed by receiving operating characteristics (ROC) analysis; correlations between HRCT scores and Ca 15.3 were performed. Survival and serial pulmonary function tasting (PFT) data were used for prognostication.

RESULTS

Ca 15.3 serum levels strongly correlated with HRCT scores (r=0.734, p<0.0001) which were predictors of survival at the 20% threshold (p=3.1∗10(-4)). Ca 15.3 had an area under ROC to detect the meaningful 20% fibrosis extent equal to 0.927 and abnormal Ca 15.3 values were capable of differentiating between patients at hi- or low-risk for progression in the group with undetermined disease extent (HR=3.209, confidence interval [CI95]=1.56-6.602, p=0.002). Ca 15.3 outperformed other PFT measures in providing a separation of survival estimates where HRCT scans are unavailable. The combined use of HRCT scores and Ca 15.3 in SSc-ILD patients was more discriminatory (HR=4.824, CI95=2.612-8.912, p<0.0001) than the staging system based on HRCT scores plus FVC (HR=2.657, CI95=1.703-4.147, p<0.0001) and characterized by lower prediction errors (0.2134 vs 0.2234).

CONCLUSION

Ca 15.3 is a rapid and inexpensive candidate biomarker for SSc-ILD being proportional to the extent of lung injury and specific and sensitive in assessing meaningful extents of the disease with prognostic significance.

Role of the clinical immunology laboratory in disease monitoring

Immunological investigations provide useful information to guide diagnosis of several disorders. Many such tests are also commonly repeated at intervals, in an effort to facilitate disease monitoring. In general however, immunology test results are often slow to alter. Furthermore, audit activity has indicated that repeated testing accounts for a substantial workload in many immunology services, which may waste resources and compromise the efficient completion of necessary tests. Consequently, the need and appropriate minimum interval between repeated testing requires critical evaluation. In this review, the clinical utility of repeated performance of several common immunology investigations has been evaluated, based upon published evidence. In some cases (e.g., paraprotein quantification, or measurement of anti-glomerular basement membrane antibodies), repeated testing provides vital clinical information and can be justified on a frequent and individualized basis. However, many other investigations provided by immunology services provide less valuable information when used to aid disease monitoring rather than diagnosis. It is hoped that the data summarized here will facilitate a more evidence-based approach to repeated testing. Such information may also assist with the local implementation of demand management strategies based upon setting of minimum retesting intervals for these investigations.

Is identification of anti-SSA and/or -SSB antibodies necessary in serum samples referred for antinuclear antibodies testing?

BACKGROUND

Anti-SSA and -SSB antibodies are clinically important antinuclear antibodies in patients with systemic rheumatic diseases.

METHODS

We evaluated fluorescence characteristics and clinical significance of anti-SSA and -SSB and explored whether identification of these antibodies was necessary in clinical application.

RESULTS

Of 4,978 consecutive samples, 259 showed anti-SSA or -SSB reactivity, clinical information of which were analyzed. Compared with SSA+SSB- and SSA-SSB+ group, SSA+SSB+ group showed a lower proportion (0.5%) of negative specimens detected with antinuclear antibody assay and a higher proportion (53.5%) of specimens with high titer. Anti-SSA- and/or -SSB-positive samples presented various patterns. However, 64.6% of SSA+SSB+ samples presented speckled pattern, significantly higher than SSA+SSB- and SSA-SSB+ samples. A total of 475 specimens containing anti-SSA or -SSB were obtained from 302 individuals. Clinical information was obtained for 259 of them, which were further analyzed. The prevalence of Sjögren syndrome (SS) was significantly higher, and that of other diseases was lower in SSA+SSB+ than in SSA+SSB- group. Of the 259 individuals, 71 anti-SSA- and/or -SSB-positive patients had blood drawn on 2 or more occasions over the 2-year study period. The number of tests per patient was 2.7 ± 1.1. In 7 of the 71 patients, anti-SSA was observed in some but not all samples, so was anti-SSB in 6.

CONCLUSION

In conclusion, the identification of anti-SSA and -SSB antibodies is necessary, when corresponding diseases are suspected. The specificity of anti-SSA for the diagnosis of SS could be improved, when combined with anti-SSB. SS patients need not be identified frequently for anti-SSA and -SSB because of their stability.

Common presentations of pediatric rheumatologic diseases: a generalist's guide

PURPOSE OF REVIEW

To present a case-based approach of three common scenarios which often present to the primary care physician. The approach to these cases and the differential diagnosis are discussed for these common rheumatologic diseases.

RECENT FINDINGS

Numerous healthy children and adolescents are referred to pediatric rheumatologists for the evaluation of suspected rheumatologic diseases. Often, general rheumatologic laboratory tests are sent which are not necessarily specific to the clinical situation. There is a high false-positive rate associated with many of these tests and undue anxiety and referrals result from these. Directed laboratory studies based on history and exam findings are more prudent and useful in the evaluation of these children. Routine antinuclear antibody testing, for example, is not recommended without supportive symptoms or signs.

SUMMARY

A practical approach for primary care physicians is described for the evaluation of patients suspected of having some of the more common pediatric rheumatologic symptoms and diseases.

Patients with idiopathic pulmonary fibrosis with antibodies to heat shock protein 70 have poor prognoses

RATIONALE

Diverse autoantibodies are present in most patients with idiopathic pulmonary fibrosis (IPF). We hypothesized that specific autoantibodies may associate with IPF manifestations.

OBJECTIVES

To identify clinically relevant, antigen-specific immune responses in patients with IPF.

METHODS

Autoantibodies were detected by immunoblots and ELISA. Intrapulmonary immune processes were evaluated by immunohistochemistry. Anti-heat shock protein 70 (HSP70) IgG was isolated from plasma by immunoaffinity. Flow cytometry was used for leukocyte functional studies.

MEASUREMENTS AND MAIN RESULTS

HSP70 was identified as a potential IPF autoantigen in discovery assays. Anti-HSP70 IgG autoantibodies were detected by immunoblots in 3% of 60 control subjects versus 25% of a cross-sectional IPF cohort (n = 122) (P = 0.0004), one-half the patients with IPF who died (P = 0.008), and 70% of those with acute exacerbations (P = 0.0005). Anti-HSP70 autoantibodies in patients with IPF were significantly associated with HLA allele biases, greater subsequent FVC reductions (P = 0.0004), and lesser 1-year survival (40 ± 10% vs. 80 ± 5%; hazard ratio = 4.2; 95% confidence interval, 2.0-8.6; P < 0.0001). HSP70 protein, antigen-antibody complexes, and complement were prevalent in IPF lungs. HSP70 protein was an autoantigen for IPF CD4 T cells, inducing lymphocyte proliferation (P = 0.004) and IL-4 production (P = 0.01). IPF anti-HSP70 autoantibodies activated monocytes (P = 0.009) and increased monocyte IL-8 production (P = 0.049). ELISA confirmed the association between anti-HSP70 autoreactivity and IPF outcome. Anti-HSP70 autoantibodies were also found in patients with other interstitial lung diseases but were not associated with their clinical progression.

CONCLUSIONS

Patients with IPF with anti-HSP70 autoantibodies have more near-term lung function deterioration and mortality. These findings suggest antigen-specific immunoassays could provide useful clinical information in individual patients with IPF and may have implications for understanding IPF progression.

Clinical significance of serum autoantibodies in idiopathic interstitial pneumonia

Although autoantibodies are routinely screened in patients with idiopathic interstitial pneumonia, there are no reliable data on their clinical usefulness. The aim of this study was to investigate the prognostic value of autoantibodies for predicting the development of new connective tissue disease in these patients and also mortality. We conducted retrospective analysis of the baseline, and follow-up data for 688 patients with idiopathic interstitial pneumonia (526 with idiopathic pulmonary fibrosis, 85 with nonspecific interstitial pneumonia, and 77 with cryptogenic organizing pneumonia) at one single tertiary referral center. The median follow-up period was 33.6 months. Antinuclear antibody was positive in 34.5% of all subjects, rheumatoid factor in 13.2%, and other specific autoantibodies were positive between 0.7%-6.8% of the cases. No significant difference in patient survival was found between the autoantibody-positive and -negative groups. However, the presence of autoantibodies, especially antinuclear antibody with a titer higher than 1:320, was a significant predictor for the future development of new connective tissue diseases (relative risk, 6.4), although the incidence was low (3.8% of all subjects during follow-up). In conclusion, autoantibodies are significant predictors for new connective tissue disease development, although they have no prognostic value.

Associations of autoantibodies, autoimmune risk alleles, and clinical diagnoses from the electronic medical records in rheumatoid arthritis cases and non-rheumatoid arthritis controls

OBJECTIVE

The significance of non-rheumatoid arthritis (RA) autoantibodies in patients with RA is unclear. The aim of this study was to assess associations of autoantibodies with autoimmune risk alleles and with clinical diagnoses from the electronic medical records (EMRs) among RA cases and non-RA controls.

METHODS

Data on 1,290 RA cases and 1,236 non-RA controls of European genetic ancestry were obtained from the EMRs of 2 large academic centers. The levels of anti-citrullinated protein antibodies (ACPAs), antinuclear antibodies (ANAs), anti-tissue transglutaminase antibodies (AGTAs), and anti-thyroid peroxidase (anti-TPO) antibodies were measured. All subjects were genotyped for autoimmune risk alleles, and the association between number of autoimmune risk alleles present and number of types of autoantibodies present was studied. A phenome-wide association study (PheWAS) was conducted to study potential associations between autoantibodies and clinical diagnoses among RA cases and non-RA controls.

RESULTS

The mean ages were 60.7 years in RA cases and 64.6 years in non-RA controls. The proportion of female subjects was 79% in each group. The prevalence of ACPAs and ANAs was higher in RA cases compared to controls (each P < 0.0001); there were no differences in the prevalence of anti-TPO antibodies and AGTAs. Carriage of higher numbers of autoimmune risk alleles was associated with increasing numbers of autoantibody types in RA cases (P = 2.1 × 10(-5)) and non-RA controls (P = 5.0 × 10(-3)). From the PheWAS, the presence of ANAs was significantly associated with a diagnosis of Sjögren's/sicca syndrome in RA cases.

CONCLUSION

The increased frequency of autoantibodies in RA cases and non-RA controls was associated with the number of autoimmune risk alleles carried by an individual. PheWAS of EMR data, with linkage to laboratory data obtained from blood samples, provide a novel method to test for the clinical significance of biomarkers in disease.

Prevalence and clinical significance of rare antinuclear antibody patterns

While some of the more frequent antinuclear (auto)antibodies (ANA) patterns such as homogenous nuclear staining have been extensively studied, the prevalence and clinical significance of rare antinuclear antibody patterns are not well understood. For the purpose of this review, we defined rare patterns as patterns occurring in less than 1% of patients that test positive on indirect immunofluorescence. The prevalence of different ANA patterns was determined in 68,128 consecutive patients who attended the outpatient clinic or were hospitalized at the University Hospitals Leuven over a 14-year period (1998-2011). To avoid bias, we only included the first sample for each patient and patients who tested positive in the period 1980-1997 were excluded. There were 9268 patients who tested positive for ANA. With the exception of the clinical association of anti-multiple nuclear dots (at higher titers) and anti-nuclear envelope autoantibodies with autoimmune liver disease, there was no good clinical association of rare ANA patterns with the diagnosis of auto-immune disorders. The most important non-autoimmune cause of rare ANA patterns was carcinoma, particularly in patients with rare cell-cycle related ANAs.

Choosing wisely: the American College of Rheumatology's Top 5 list of things physicians and patients should question

OBJECTIVE

We sought to develop a list of 5 tests, treatments, or services commonly used in rheumatology practice whose necessity or value should be questioned and discussed by physicians and patients.

METHODS

We used a multistage process combining consensus methodology and literature reviews to arrive at the American College of Rheumatology's (ACR) Top 5 list. Rheumatologists from diverse practice settings generated items using the Delphi method. Items with high content agreement and perceived high prevalence advanced to a survey of ACR members, who comprise >90% of the US rheumatology workforce. To increase the response rate, a nested random sample of 390 rheumatologists received more intensive survey followup. The samples were combined and weighting procedures were applied to ensure generalizability. Items with high ratings underwent literature review. Final items were then selected and formulated by the task force.

RESULTS

One hundred five unique items were proposed and narrowed down to 22 items during the Delphi rounds. A total of 1,052 rheumatologists (17% of those contacted) participated in the member-wide survey, whereas 33% of those in the nested random sample participated; respondent characteristics were similar in both samples. Based on survey results and available scientific evidence, 5 items (relating to antinuclear antibodies, Lyme disease, magnetic resonance imaging, bone absorptiometry, and biologic therapy for rheumatoid arthritis) were selected for inclusion.

CONCLUSION

The ACR Top 5 list is intended to promote discussions between physicians and patients about health care practices in rheumatology whose use should be questioned and to assist rheumatologists in providing high-value care.

An autoinflammatory neurological disease due to interleukin 6 hypersecretion

Autoinflammatory diseases are rare illnesses characterized by apparently unprovoked inflammation without high-titer auto-antibodies or antigen-specific T cells. They may cause neurological manifestations, such as meningitis and hearing loss, but they are also characterized by non-neurological manifestations. In this work we studied a 30-year-old man who had a chronic disease characterized by meningitis, progressive hearing loss, persistently raised inflammatory markers and diffuse leukoencephalopathy on brain MRI. He also suffered from chronic recurrent osteomyelitis of the mandible. The hypothesis of an autoinflammatory disease prompted us to test for the presence of mutations in interleukin-1-pathway genes and to investigate the function of this pathway in the mononuclear cells obtained from the patient. Search for mutations in genes associated with interleukin-1-pathway demonstrated a novel NLRP3 (CIAS1) mutation (p.I288M) and a previously described MEFV mutation (p.R761H), but their combination was found to be non-pathogenic. On the other hand, we uncovered a selective interleukin-6 hypersecretion within the central nervous system as the likely pathogenic mechanism. This is also supported by the response to the anti-interleukin-6-receptor monoclonal antibody tocilizumab, but not to the recombinant interleukin-1-receptor antagonist anakinra. Exome sequencing failed to identify mutations in other genes known to be involved in autoinflammatory diseases. We propose that the disease described in this patient might be a prototype of a novel category of autoinflammatory diseases characterized by prominent neurological involvement.

Systemic sclerosis: demographic, clinical and serological features in 100 Iranian patients

To evaluate demographic, clinical and laboratory features associated with scleroderma-specific auto-antibodies. Sera of 100 patients with systemic sclerosis (SSc) were analyzed by an indirect immunofluorescence technique with HEp-2 cells as a substrate. Specific ANA such as anti-centromere antibodies (ACA), anti-topoisomerase (TOPO), anti-RNA polymerase III (Pol 3), anti-U3-RNP (U3-RNP), anti-Th/To (Th/To) and anti-PM/Scl (PM/Scl) were detected by line immunoassay and anti-U1-RNP (U1-RNP) by ELISA. Frequency of clinical features associated with a specific antibody group was reported cumulatively over the follow-up period. Frequency of specific clinical features was compared across the two disease subtype including limited cutaneous (lcSSc) or diffuse cutaneous (dcSSc) as well as the auto-antibody groups. Ninety-four percent of patients were ANA positive with significant higher skin score, Raynauds and digital ulcer/gangrene. Anti-TOPO was detected in 71% of all patients, in 90.5% of dcSSC and in 65.8% of lcSSc. Anti-TOPO was significantly associated with dcSSc, higher skin score, digital ulcer/gangrene, pulmonary fibrosis, DLCO <70%. U1-RNP antibody was associated with lower fibrosis in lung. ACA was positive in 7% of patients and exclusively in those with lcSSc. We did not find association between gender and presence of auto-antibodies. Anti-TOPO antibody had a high prevalence in contrast to low prevalence of ACA antibody. There were no differences in clinical subtypes of the disease in patients with positive anti-TOPO and positive ACA. Differences in prevalence of auto-antibodies are suggestive of further genetic study.

An evaluation of autoimmune antibody testing patterns in a Canadian health region and an evaluation of a laboratory algorithm aimed at reducing unnecessary testing

Autoantibody tests are often ordered inappropriately. We aimed to evaluate the ordering patterns of these tests in our local health region and to develop a laboratory algorithm aimed at reducing unnecessary tests. Laboratory data including the number and sequence of tests, ordering physician specialties and results for antinuclear (ANA), extractable nuclear antigen (ENA) and anti-double stranded DNA (anti-dsDNA) antibody tests from 2007 to 2009 were evaluated. Based on this information and a clinical consensus meeting, an algorithm was developed and applied retrospectively to 1 year of inpatient laboratory data to simulate potential cost savings. We identified a large volume of these autoantibody tests performed, equating to testing costs of $862,706.72, where less than 17 % of each were positive. Repeated ANA tests were mostly ordered after a previously negative result, and 1 % of patients with negative results changed to ≥1:160 on repeat testing. Close to half of all ENA and anti-dsDNA tests that were ordered were done so simultaneously with ANA, suggesting their use as screening tests. This was done more frequently in the inpatient setting. An algorithm was developed where ENA and anti-dsDNA tests would be cancelled if ANA was negative in the same sample. ANA repeated within 1 year would be cancelled and the prior result provided. Application of the algorithm retrospectively simulated a 30 % cost savings. Repeat testing and simultaneous ordering of multiple tests contributed to the excessive ordering of autoantibody tests in our health region. Our proposed algorithm would reduce testing costs and should be accompanied by appropriate educational information for physicians.

Vasculitic neuropathy

Vasculitis is a primary phenomenon in autoimmune diseases such as polyarteritis nodosa, Wegener's granulomatosis, Churg-Strauss syndrome, microscopic polyangiitis, and essential mixed cryoglobulinemia. As a secondary feature vasculitis may complicate, for example, connective tissue diseases, infections, malignancies, and diabetes. Vasculitic neuropathy is a consequence of destruction of the vessel wall and occlusion of the vessel lumen of small epineurial arteries. Sometimes patients present with nonsystemic vasculitic neuropathy, i.e., vasculitis limited to peripheral nerves and muscles with no evidence of further systemic involvement. Treatment with corticosteroids, sometimes in combination with other immunosuppressants, is required to control the inflammatory process and prevent further ischemic nerve damage.

New platform technology for comprehensive serological diagnostics of autoimmune diseases

Antibody assessment is an essential part in the serological diagnosis of autoimmune diseases. However, different diagnostic strategies have been proposed for the work up of sera in particular from patients with systemic autoimmune rheumatic disease (SARD). In general, screening for SARD-associated antibodies by indirect immunofluorescence (IIF) is followed by confirmatory testing covering different assay techniques. Due to lacking automation, standardization, modern data management, and human bias in IIF screening, this two-stage approach has recently been challenged by multiplex techniques particularly in laboratories with high workload. However, detection of antinuclear antibodies by IIF is still recommended to be the gold standard method for antibody screening in sera from patients with suspected SARD. To address the limitations of IIF and to meet the demand for cost-efficient autoantibody screening, automated IIF methods employing novel pattern recognition algorithms for image analysis have been introduced recently. In this respect, the AKLIDES technology has been the first commercially available platform for automated interpretation of cell-based IIF testing and provides multiplexing by addressable microbead immunoassays for confirmatory testing. This paper gives an overview of recently published studies demonstrating the advantages of this new technology for SARD serology.

Automated indirect immunofluorescence evaluation of antinuclear autoantibodies on HEp-2 cells

Indirect immunofluorescence (IIF) on human epithelial (HEp-2) cells is considered as the gold standard screening method for the detection of antinuclear autoantibodies (ANA). However, in terms of automation and standardization, it has not been able to keep pace with most other analytical techniques used in diagnostic laboratories. Although there are already some automation solutions for IIF incubation in the market, the automation of result evaluation is still in its infancy. Therefore, the EUROPattern Suite has been developed as a comprehensive automated processing and interpretation system for standardized and efficient ANA detection by HEp-2 cell-based IIF. In this study, the automated pattern recognition was compared to conventional visual interpretation in a total of 351 sera. In the discrimination of positive from negative samples, concordant results between visual and automated evaluation were obtained for 349 sera (99.4%, kappa = 0.984). The system missed out none of the 272 antibody-positive samples and identified 77 out of 79 visually negative samples (analytical sensitivity/specificity: 100%/97.5%). Moreover, 94.0% of all main antibody patterns were recognized correctly by the software. Owing to its performance characteristics, EUROPattern enables fast, objective, and economic IIF ANA analysis and has the potential to reduce intra- and interlaboratory variability.

Application of linear discriminant analysis in performance evaluation of extractable nuclear antigen immunoassay systems in the screening and diagnosis of systemic autoimmune rheumatic diseases

This study applied a linear discriminant analysis model to evaluate the performance of 2 types of commercially available extractable nuclear antigen (ENA) immunoassays for the screening and diagnosis of systemic autoimmune rheumatic diseases (SARDs) in a large tertiary hospital reference laboratory: (1) an enzyme-linked immunosorbent assay (ELISA) and (2) a multiplex bead-based immunoassay (MPBI). The results of the study showed both ENA immunoassays had comparable sensitivity for the detection of SARDs compared with the antinuclear antigen immunofluorescence (ANA-IF) method (ANA-IF: 85.6%, ENA-ELISA: 91.5%, ENA-MPBI: 83.1%, pairwise comparisons with ANA-IF: P > .05). However, both ENA immunoassays offered improved specificity compared with the ANA-IF (ANA-IF: 24.2%; ENA-ELISA: 39.8%; ENA-MPBI: 53.1%; pairwise comparison with ANA-IF: P < .001). The use of a more specific screening immunoassay with comparable sensitivity to ANA-IF is important in a tertiary hospital with high prevalence of non-SARD immune diseases. Diagnostic performance of the ENA/dsDNA components by the MPBI and ELISA methods did not differ significantly (area under the curve [AUC], 81.0% vs 83.0%, respectively, P > .05), but the key ENA/dsDNA variables contributing to the discriminating power of the assays for the diagnosis of specific SARDs were reagent/method dependent.

Autoantibodies in scleroderma and their association with the clinical profile of the disease. A study of 66 patients from southern Brazil

BACKGROUND

Scleroderma is a fairly rare connective tissue disease whose autoantibody profile is associated with different clinical manifestations. The prevalence of autoantibodies in scleroderma is influenced by race and genetics.

OBJECTIVE

To study the prevalence of anti-Scl-70, anti-centromere (ACA) and anti-U1-RNP antibodies in patients with scleroderma in southern Brazil and verify their association with clinical manifestations of the disease.

METHODS

A retrospective study involving 66 patients with scleroderma for the presence of anti-Scl-70, anti-centromere and anti-U1-RNP and of clinical manifestations such as Raynaud's phenomenon, digital micro scars, digital necrosis, telangiectasias, calcinosis, pulmonary fibrosis, pleuritis, pericarditis, cardiomyopathy, arthralgia and arthritis, skin sclerosis, joint contractures, tendon friction rubs, pulmonary hypertension, esophageal disorders and renal crisis.

RESULTS

The prevalence of anti-Scl-70 was 17.8% , that of ACA was 33.3% and the prevalence of U1 RNP was 11.8%. Anti-Scl-70 was associated with the diffuse form of the disease (p = 0.015), presence of cardiomyopathies (p = 0.016) and digital micro scars (p = 0.05). Anti-centromere was more common in the limited form, although it was not statistically significant, and had a protective role associated with cardiomyopathies (p = 0.005). Anti-U1-RNP was more common in the overlap forms (p = 0.0004).

CONCLUSION

The prevalence and profile of clinical associations of autoantibodies in Brazilian patients with scleroderma are similar to those found in the literature.

[Laboratory diagnostics for early detection of rheumatic autoimmune diseases: a guide for the general practitioner]

Autoimmune diseases are a clinically heterogeneous group of disorders that represent a challenge for the general practitioner in daily routine. Except for rheumatoid arthritis, which is one of the most frequent autoimmune diseases with a prevalence of approximately 1 % of the population, systemic autoimmune disorders are rare. Thus outside specialized wards it might be a challenge to diagnose the underlying autoimmune disease considering the often kaleidoscopic clinical manifestations. Together with careful anamnesis and suspicious clinical symptoms determination of specific autoantibodies can support the suspected diagnosis. The Austrian group of the European autoimmune standardization initiative (EASI) firstly published this guide 2009 with the aim to provide a map through the jungle of the biomarkers for autoimmune diseases for the general practitioner.

Geographical differences in autoantibodies and anti-infectious agents antibodies among healthy adults

Much is known about the geoepidemiology of defined autoimmune diseases (AD); however, there is currently limited data regarding the prevalence of autoantibodies among healthy populations of different geographical areas. The aim of this study was to evaluate a large profile of autoantibodies in healthy adults from distinct global regions as well as the prevalence of anti-infectious agents antibodies in those regions. Sera samples from 557 healthy donors were obtained at six centers located in different countries (i.e., Italy, Netherlands, Israel, Mexico, Columbia, Papua New Guinea (Kitavans)). Sera were tested for the presence of antinuclear antibodies (ANA) and autoantibodies associated with thrombophilia, vasculitis, and gastrointestinal (GI) disease. Sera samples were also screened for antibodies against infectious agents (i.e., EBV, CMV, HBV, Helicobacter pylori, Treponema pallidum, and Toxoplasma gondii). Tests were performed using the BioPlex 2200 or ELISA kits (Bio-Rad Laboratories, USA). We found a significant gradient of ANA positivity among the groups: 45% of Columbians, 38% of Kitavans, 26% of Mexicans, 12% of Italians, 12% of Dutch, and 11% of Israelis were ANA positive. Geographical differences were also observed regarding the prevalence of specific autoantibodies, namely ANA: anti-dsDNA, chromatin, SmRNP, Ro/SSA, La/SSB, Scl70; GI associated: antigliadin; and thrombophilia-associated: anti-β2GP1 and prothrombin. Additionally, significant differences were observed regarding serological markers of all infectious agents screened. The observed variance between healthy ethno-geographical distinct populations in prevalence of autoantibodies may represent different genetic or environmental (e.g., prior exposure to infection) influences. Thus may illuminate possible causes of geoepidemiological differences in AD.

Automation in indirect immunofluorescence testing: a new step in the evolution of the autoimmunology laboratory

Indirect immunofluorescence (IIF) plays an important role in immunological and immunometric assays for detecting and measuring autoantibodies. This technology was the first multiplex method used to detect cardinal autoantibodies for the diagnosis of autoimmune diseases. Over the last 20 years, research has enabled the progressive identification of cell and tissue autoantigens which are the target of autoantibodies originally detected by IIF. Accordingly, newer immunometric methods, capable of measuring concentrations of specific autoantibodies directed against these autoantigens, allowed for a gradual replacement of the IIF method in the autoimmunology laboratory. Currently, IIF remains the method of choice only in selected fields of autoimmune diagnostics. Following the recent statement by the American College of Rheumatology that the IIF technique should be considered as the standard screening method for the detection of ANA, the biomedical industry has developed technological solutions which significantly improve automation of the procedure, not only in the preparation of substrates and slides, but also in microscope reading. This review summarizes the general and specific features of new available commercial systems (Aklides, Medipan; Nova View, Inova; Zenit G Sight, A. Menarini Diagnostics; Europattern, Euroimmun; Helios, Aesku.Diagnostics; Image Navigator, Immuno Concepts; Cytospot, Autoimmun Diagnostika) for automation of the IIF method. The expected advantages of automated IIF are the reduction in frequency of false negative and false positive results, the reduction of intra- and inter-laboratory variability, the improvement of correlation of staining patterns with corresponding autoantibody reactivities, and higher throughput in the laboratory workflow.

Biomarkers for systemic lupus erythematosus

In recent years, biomarkers have shown significant promise in helping decision-making in drug development. Systemic lupus erythematosus (SLE) is a complicated and highly heterogeneous disease that involves all organs. Only one drug, belimumab, has been approved by the US Food and Drug Administration to treat SLE during the last 50 years and there remains a high unmet medical need to develop new and effective therapies to benefit different patient populations in SLE. Due to the extreme heterogeneity of the disease and the complex and rigorous process to validate individual biomarkers, there is currently a very limited number of consensus biomarkers to aid the treatment decision-making in SLE. This review provides a snapshot of some biomarkers in the field that have the potential to make a big impact on drug development and/or treatment decisions by physicians. These include: type I interferon (IFN) gene signature as a pharmacodynamic marker and potential predictive marker for anti-type I IFN therapy; anti-double stranded DNA as a disease marker and potential predictive marker for flares; the complements and neutrophil signatures as disease marker of SLE; and TWEAK (a tumor necrosis factor family member produced by macrophages) and MCP-1 as potential markers to predict renal flares. Most of these markers need carefully planned and prospective studies with high statistical power to confirm their respective utilities. With the development and application of powerful new technologies, more successful biomarkers will emerge in SLE. This could improve the management of patients in the clinic and facilitate the development of novel and more effective therapeutics for this difficult-to-treat disease.

Clinical utility and implications of asparaginase antibodies in acute lymphoblastic leukemia

Hypersensitivity to asparaginase is common, but the differential diagnosis can be challenging and the diagnostic utility of antibody tests is unclear. We studied allergic reactions and serum antibodies to E. coli asparaginase (Elspar) in 410 children treated on St. Jude Total XV protocol for acute lymphoblastic leukemia. Of 169 patients (41.2%) with clinical allergy, 147 (87.0%) were positive for anti-Elspar antibody. Of 241 patients without allergy, 89 (36.9%) had detectable antibody. Allergies (P=0.0002) and antibodies (P=6.6 × 10(-6)) were higher among patients treated on the low-risk arm than among those treated on the standard/high-risk arm. Among those positive for antibody, the antibody titers were higher in those who developed allergy than in those who did not (P<1 × 10(-15)). Antibody measures at week 7 of continuation therapy had a sensitivity of 87-88% and a specificity of 68-69% for predicting or confirming clinical reactions. The level of antibodies was inversely associated with serum asparaginase activity (P=7.0 × 10(-6)). High antibody levels were associated with a lower risk of osteonecrosis (odds ratio=0.83; 95% confidence interval, 0.78-0.89; P=0.007). Antibodies were related to clinical allergy and to low systemic exposure to asparaginase, leading to lower risk of some adverse effects of therapy.

Using the antinuclear antibody test to diagnose rheumatic diseases: when does a positive test warrant further investigation?

The anti-nuclear antibody (ANA) test is ordered commonly as a screening test for rheumatic diseases. Although ANA positivity is highly sensitive for certain rheumatic diseases, the presence of ANA is nonspecific and can be associated with numerous nonrheumatic factors, including environmental exposures, malignancies, drugs, and infections. This article describes a practical approach for physicians when evaluating patients using a positive ANA test. In the absence of connective tissue disease symptoms, the ANA test has minimal clinical significance in diagnosing rheumatic diseases. Understanding how to use ANA test results appropriately may reduce unnecessary referrals and costly workups.