Evaluation of a Fully Automated Antinuclear Antibody Indirect Immunofluorescence Assay in Routine Use

Harmonization of ANA testing challenge: quantification strategy to accurately predict end-point titers avoiding serial dilution

Despite the advantages of automated systems for antinuclear antibody (ANA) analysis, the prediction of end-point titers avoiding serial dilutions is still in progress. The aims of this study were to set a conversion table providing discriminant ranges of fluorescence signal intensity values (FI) corresponding to the end-point titers and validate this tool in a real-life laboratory setting. Eight hundred ninety-four serum samples were analyzed for ANA using Image Navigator System. In order to classify FI into non-overlapping groups corresponding to conventional end-point titers, statistical discriminant analysis was used. Validation study was performed calculating agreement and error rates between visual readings and conversion table of 1119 routine ANA positive samples. Setting of FI ranges corresponding to the end-point titers for different staining patterns was computed. For samples showing single pattern, the overall agreement between visual readings and conversion table was 98.4% for all titers ranging from 1:160 to 1:2560, of which 68.0% had the same titer and 30.4% were within ± one titer difference. Concordance rates according to ANA patterns were as follows: (1) nuclear 98.4%, of which 67.0% had the same titer and 31.4% ± one titer; (2) cytoplasmic 100%, of which 72.7% had the same titer and 27.3% than ± one titer; (3) mitotic 66.6%, of which 33.3% had more ± one titer. Our study developed a quantification method for autoantibodies titers assessment based on just one single sample dilution instead of traditional serial dilution approach, providing significant advantages in routine laboratory in terms of reduction in hand-on time and harmonization of results.

A novel way to evaluate autoantibody interference in samples with mixed antinuclear antibody patterns in the HEp-2 cell based indirect immunofluorescence assay and comparison of conventional microscopic and computer-aided pattern recognition

BACKGROUND

A major challenge of the HEp-2 cell-based indirect immunofluorescence (IIF) assays is the correct identification of the individual anti-nuclear antibodies (ANAs) if more than one is present in a sample. We created artificial mixes by pooling two different samples with a single autoantibody in different titers. Comparison of the expected and observed patterns and titers clarifies the interference between the two tested ANAs.

METHODS

Serum samples with a single homogeneous or speckled ANA pattern were serially diluted and mixed in 16 combinations, providing end-point titers of 1:5,120 to 1:80 for both patterns. These mixes were tested by a HEp-2 IIF assay and were evaluated by conventional evaluation, the EUROPattern (EPa) system and on-screen analysis.

RESULTS

Homogeneous pattern can alter the identification of the speckled pattern much more than vice versa, but both has an interfering effect on the other. The effect of the interfering on the tested pattern was higher if the titer of the former one was higher. The pattern recognition efficacy of conventional and the on-screen evaluation was similar and superior compared to the EPa analysis.

CONCLUSIONS

The application of artificial mixed samples can help the evaluation of the efficacy of manual and computer-aided ANA HEp-2 pattern recognition.

Significance of co-positivity for anti-dsDNA, -nucleosome, and -histone antibodies in patients with lupus nephritis

OBJECTIVE

The aim of this study was to define the clinical, histopathologic, and prognostic features associated with simultaneous positivity for anti-dsDNA, -nucleosome, and -histone antibodies (3-pos) in Korean patients with biopsy-proven lupus nephritis (LN).

METHODS

The 102 patients included in the study had undergone kidney biopsy prior to the start of induction treatment, were treated with immunosuppressives, and followed-up for >12 months.

RESULTS

In total, 44 (43.1%) of the 102 LN patients were 3-pos. Patients with 3-pos had a higher SLEDAI-2K score (p = .002), lower lymphocyte count (p = .004), and higher rates of proteinuria > 3.5 g/24 h (p = .039) and positivity for urinary sediments (p = .005) at the time of renal biopsy than non-3-pos patients. 3-pos patients had a more proliferative form of LN (p = .045) in the renal histopathologic findings, and as co-positivity gradually increased from 0 to 3, the total activity score in the renal biopsy findings increased significantly (p = .033). In addition, 3-pos patients had a more rapid eGFR decline than non-3-pos patients after a follow-up of 83.2 months (p = .016).

CONCLUSIONS

Our findings suggest that 3-pos is related to severe LN and that 3-pos patients are more likely to experience a rapid decline of renal function than non-3-pos patients.KEY MESSAGEPatients with co-positivity for anti-dsDNA, -nucleosome, and -histone antibodies (3-pos) had higher disease activity and a worse renal histopathology than those without co-positivity.3-pos patients had a more rapid decline of renal function than non-3-pos patients.

The Risk of Autoimmunity Development following mRNA COVID-19 Vaccination

The broad spectrum of interactions between autoimmune diseases and the SARS-CoV-2 vaccination is not fully understood. This study aims to evaluate the prevalence of anti-nuclear antibodies (ANA), anti-ENA, anticardiolipin antibodies (ACL), and anti-beta-2 glycoprotein I antibodies (anti-β2GPI) before and after the SARS-CoV-2 mRNA vaccination in a real-life setting in healthcare professionals. The identification of risk factors associated with vaccine immunogenicity was evaluated. The study group consisted of employees of two hospitals (354 individuals). Samples for antibody assays were collected before vaccination and at 7-9 months after complete immunisation. There was no significant increase in the prevalence of ANA, ACL or anti-β2GPI antibodies, or autoimmune diseases in subjects who were vaccinated 7-9 months after complete immunisation. In terms of detected anti-ENA, the anti-DFS70 antibodies were found in 6 times more subjects than before vaccination at the second blood draw (in 18 and 3 subjects, respectively) (p = 0.001). There were no significant relationships between a SARS-CoV-2 infection history, humoral response, cellular response, subject category, smoking, sex, body weight, ANA, anti-ENA, ACL, or anti-β2GPI. This study revealed a possible association between the severity of vaccine adverse events (VAEs) and ANA titre. Individuals with more severe VAEs (>10 points) after the second dose of the vaccine had significantly higher ANA titre after complete immunization. When analysing the significance of time between the ANA, anti-ENA, ACL, and anti- β2GPI assays and complete immunisation antibody values, no qualitative result was statistically significant. There was correlation between the time since complete immunization and ANA after.

An indirect comparison of automated indirect immunofluorescence vs automated solid-phase immunoassays for antinuclear antibody detection: A meta-analysis and adjusted indirect comparison of diagnostic test accuracy

OBJECTIVE

The primary aim of this study was to conduct a meta-analysis to compare the diagnostic accuracy of automated indirect immunofluorescence (automated-IIF) and fully automated solid-phase immunoassays (solid-phase assays), compared with gold standard conventional manual indirect immunofluorescence (manual-IIF) for antinuclear antibody (ANA) detection.

METHODS

Indirect meta-comparison was performed using prospective studies reporting comparative data between automated-IIF and fully automated solid-phase assays individually to conventional manual-IIF. Diagnostic tests regarding different automated solid-phase assays and automated-IIF for ANA detection were retrieved from the Cochrane Library, PubMed, Embase, Web of Science, Chinese Biological Medicine Database (CBM), China National Knowledge Infrastructure (CNKI), and WANFANG electronic databases from their inception to January 2022. Assessment of the quality of the studies was undertaken using a second version of the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. The investigated diagnostic indices including pooled sensitivity, pooled specificity, pooled positive likelihood ratio (PLR), pooled negative likelihood ratio (NLR), pooled diagnostic odds ratio (DOR), area under the summary receiver operating characteristic (AUC) of automated-IIF and solid-phase assays, respectively. Relative diagnostic odds ratio (RDOR) was calculated to indirectly compare the diagnostic accuracy of automated-IIF and solid-phase assays. To visualize results, we provide forest plots showing the RDOR with 95% confidence intervals (CI) of the 2 methods against the "gold standard" manual-IIF by R software. Deeks' funnel was used to investigate the publication bias.

RESULTS

A total of 16 studies involving 6111 subjects were included in the analysis. The pooled sensitivity, pooled specificity, pooled PLR, pooled NLR, pooled DOR and the AUC were 0.85 (95% CI: 0.84-0.86), 0.82 (95% CI 0.81-0.84), 14.22 (95% CI 8.55-23.65), 0.06 (95% CI 0.03-0.12), 287.0 (95% CI 124.30-662.68) and 0.983 for automated-IIF respectively, and as for solid-phase assays those were 0.73 (95% CI 0.70-0.75), 0.87 (95% CI 0.85-0.89), 5.66 (95% CI 3.33-9.62), 0.30 (95% CI 0.20-0.47), 19.14 (95% CI 8.00-45.79) and 0.894. The results of indirect comparison indicated that automated-IIF had statistically significant higher accuracy for the detection of ANA.

CONCLUSION

This meta-analysis and indirect comparison suggest that automated-IIF should be recommended as an alternative assay for ANA screening under the condition of increased demand for ANA testing in clinical immunology laboratories.

Systemic Sclerosis-Specific Antibodies: Novel and Classical Biomarkers

Disease-specific autoantibodies are considered the most important biomarkers for systemic sclerosis (SSc), due to their ability to stratify patients with different severity and prognosis. Anti-nuclear antibodies (ANA), occurring in subjects with isolated Raynuad's phenomenon, are considered the strongest independent predictors of definite SSc and digital microvascular damage, as observed by nailfold videocapillaroscopy. ANA are present in more than 90% of SSc, but ANA negativity does not exclude SSc diagnosis: a little rate of SSc ANA negative exists and shows a distinct subtype of disease, with less vasculopathy, but more frequent lower gastrointestinal involvement and severe disease course. Anti-centromere, anti-Th/To, and anti-Topoisomerase I antibodies could be considered as classical biomarkers, covering about 60% of SSc and defining patients with well-described cardio-pulmonary complications. In particular, anti-Topoisomerase I represent a risk factor for development of diffuse cutaneous involvement and digital ulcers in the first 3 years of disease, as well as severe interstitial lung disease (ILD). Anti-RNA polymerase III is a biomarker with new clinical implications: very rapid skin thickness progression, gastric antral vascular ectasia, the occurrence of synchronous cancers, and possible association with silicone breast implants rupture. Moreover, novel SSc specific autoantibodies have been globally described in about 10% of "seronegative" SSc patients: anti-elF2B, anti-RuvBL1/2 complex, anti-U11/U12 RNP, and anti-BICD2 depict specific SSc subtypes with severe organ complications. Many autoantibodies could be considered markers of overlap syndromes, including SSc. Anti-Ku are found in 2-7% of SSc, strictly defining the PM/SSc overlap. They are associated with synovitis, joint contractures, myositis, and negatively associated with vascular manifestation of disease. Anti-U3RNP are associated with a well-defined clinical phenotype: Afro-Caribbean male patients, younger at diagnosis, and higher risk of pulmonary hypertension and gastrointestinal involvement. Anti-PM/Scl define SSc patients with high frequency of ILD, calcinosis, dermatomyositis skin changes, and severe myositis. The accurate detection of autoantibodies SSc specific and associated with overlap syndromes is crucial for patients' stratification. ANA should be correctly identified using indirect immunofluorescent assay and a standardized way of patterns' interpretation. The gold-standard technique for autoantibodies' identification in SSc is still considered immunoprecipitation, for its high sensitivity and specificity, but other assays have been widely used in routine practice. The identification of SSc autoantibodies with high diagnostic specificity and high predictive value is mandatory for early diagnosis, a specific follow-up and the possible definition of the best therapy for every SSc subsets. In addition, the validation of novel autoantibodies is mandatory in wider cohorts in order to restrict the gap of so-called seronegative SSc patients.

Diagnostic Value of Anti-Nuclear Antibodies: Results From Korean University-Affiliated Hospitals

BACKGROUND

Unnecessary and inappropriate laboratory testing accounts for a significant portion of waste in health care utilization. The aim of this study was to examine the diagnostic value of the anti-nuclear antibody (ANA) test by examining the rate of ANA associated rheumatic disease (AARD) diagnosis among ANA tested and ANA positive subjects and positive predictive value (PPV) of ANA test leading to AARD diagnosis in different ANA titers and different subsets of patients in 5 hospitals affiliated with a university.

METHODS

We retrospectively extracted data from all subjects who were tested for ANA from year 2010 to 2019. Those who were first evaluated at or referred to rheumatology were further evaluated with extraction of data including ANA titer and ultimate diagnosis. PPVs for ANA test were evaluated after stratification according to clinically relevant key parameters, such as patient age (younger < 65 years vs. older), sex, and requesting department.

RESULTS

From 2010 to 2019, A total of 94,153 patients were tested for ANA, of which 13,600 (14.4% of the total) were positive. AARD was diagnosed in only 0.69% among all ANA tested patients and 4.74% among ANA positive patients. The AARD diagnosis rate of ANA positive patients varied widely from 0.1% to 8.7% by requesting department. Using cutoff values above 1:320 yielded PPVs of 15.6 and 7.8% for all AARs and systemic lupus erythematosus. The PPV was significantly higher in young age (< 65 years) and in women, and when it was requested from internal medicine vs other departments.

CONCLUSION

AARD was diagnosed in less than 1% of all ANA tested patients in university-affiliated hospitals. This result shows that careful consideration before ordering the screening ANA is needed to improve the utility of the test for providers and patients and to reduce health costs spurred by unnecessary testing and its consequences.