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Rheumatoid arthritis (RA) is a systemic autoimmune disease characterised by the presence of autoantibodies that are used for classification of the disease. Though routine diagnostics is commonly restricted to measuring rheumatoid factor (RF) and anti-citrullinated protein antibodies, detection of RF IgM, IgG and IgA isotypes, may increase the power of RA serodiagnosis by reducing the number of seronegative patients as well as provide prognostic information. The agglutination-based RF assays, such as nephelometry or turbidimetry, are unable to differentiate isotypes. We compared three different immunoassays used in current laboratory practice to detect RF isotypes. We tested 117 consecutive serum samples that were positive for total RF at nephelometry, from 55 RA and 62 non-RA subjects. IgA, IgG, and IgM isotypes of RF were tested by immunoenzymatic (ELISA, Technogenetics), fluoroenzymatic (FEIA, ThermoFisher) and chemiluminescence (CLIA, YHLO Biotech Co.) immunoassays. Diagnostic performance differed considerably between the assays, especially with regard to RF IgG isotype. Agreement among methods by Cohen's kappa ranged from 0.05 (RF IgG CLIA vs. FEIA) to 0.846 (RF IgM CLIA vs. FEIA). The poor agreement observed in this study indicates substantial lack of comparability among assays for RF isotypes. Harmonization of these tests requires further efforts before their measurement can be used in clinical practice. [ABSTRACT FROM AUTHOR]

Antinuclear antibodies (ANA) are important for the diagnosis of various autoimmune diseases. ANA are usually detected by indirect immunofluorescence assay (IFA) using HEp-2 cells (HEp-2 IFA). There are many variables influencing HEp-2 IFA results, such as subjective visual reading, serum screening dilution, substrate manufacturing, microscope components and conjugate. Newer developments on ANA testing that offer novel features adopted by some clinical laboratories include automated computer-assisted diagnosis (CAD) systems and solid phase assays (SPA). A group of experts reviewed current literature and established recommendations on methodological aspects of ANA testing. This process was supported by a two round Delphi exercise. International expert groups that participated in this initiative included (i) the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) Working Group "Autoimmunity Testing"; (ii) the European Autoimmune Standardization Initiative (EASI); and (iii) the International Consensus on ANA Patterns (ICAP). In total, 35 recommendations/statements related to (i) ANA testing and reporting by HEp-2 IFA; (ii) HEp-2 IFA methodological aspects including substrate/conjugate selection and the application of CAD systems; (iii) quality assurance; (iv) HEp-2 IFA validation/verification approaches and (v) SPA were formulated. Globally, 95% of all submitted scores in the final Delphi round were above 6 (moderately agree, agree or strongly agree) and 85% above 7 (agree and strongly agree), indicating strong international support for the proposed recommendations. These recommendations are an important step to achieve high quality ANA testing. [ABSTRACT FROM AUTHOR]

The vulnerable population of kidney transplant recipients (KTRs) are low responders to COVID-19 vaccines, so specific immune surveillance is needed. The interferon-gamma (IFN-γ) release assay (IGRA) is effective in assessing T cell-mediated immunity. We assessed SARS-CoV-2-directed T cell responses in KTRs with absent antibody production after a third dose of the mRNA-1273 vaccine, using two different IGRAs. A cohort of 57 KTRs, who were actively followed up, received a third dose of the mRNA-1273 vaccine. After the evaluation of humoral immunity to SARS-CoV-2, 14 seronegative patients were tested with two commercial IGRAs (SD Biosensor and Euroimmun). Out of 14 patients, one and three samples were positive by IGRAs with Euroimmun and SD Biosensor, respectively. The overall agreement between the two assays was 85.7% (κ = 0.444). In addition, multivariate linear regression analysis showed no statistically significant association between the IFN-γ concentration, and the independent variables analyzed (age, gender, years since transplant, total lymphocytes cells/mcl, CD3+ cells/mcl, CD3+ CD4+ cells/mcl, CD3+ CD8+ cells/mcl, CD19+ cells/mcl, CD3-CD16+CD56+ cells/mcl) (p > 0.01). In a vulnerable setting, assessing cellular immune response to complement the humoral response may be advantageous. Since the two commercial IGRAs showed a good agreement on negative samples, the three discordant samples highlight the need for further investigations. [ABSTRACT FROM AUTHOR]

Immune response, vaccine, antibody kinetics, anti-SARS-CoV-2 antibodies, health care workers, neutralizing antibodies, surrogate virus neutralization test Keywords: antibody kinetics; anti-SARS-CoV-2 antibodies; health care workers; immune response; neutralizing antibodies; surrogate virus neutralization test; vaccine EN antibody kinetics anti-SARS-CoV-2 antibodies health care workers immune response neutralizing antibodies surrogate virus neutralization test vaccine 934 940 7 05/12/22 20220501 NES 220501 Introduction Since the beginning of the coronavirus disease (COVID-19) pandemic [[1]], the public health measures implemented to prevent the spread of the Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2) has led to social, political, and economic consequences [[2]]. Healthy individuals show high levels of the anti-SARS-CoV-2 Spike S1 protein IgG (anti-S1 IgG) antibodies and NAbs, as well as a persistent germinal center B-cell response following vaccination [[15]], [[16]], [[17]], [[18]], [[19]], [[20]], [[21]], [[22]]. [Extracted from the article]

During coronavirus disease 2019 (COVID‐19) pandemic, the early diagnosis of patients is a priority. Serological assays, in particular immunoglobulin (Ig)M and IgG anti‐severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), have today several applications but the interpretation of their results remains an open challenge. Given the emerging role of the IgA isotype in the COVID‐19 diagnostics, we aimed to identify the SARS‐CoV‐2 IgA antibodies in a COVID‐19 population seronegative for IgM. A total of 30 patients hospitalized in San Giovanni di Dio Hospital (Florence, Italy) for COVID‐19, seronegative for IgM antibodies, have been studied for anti‐SARS‐CoV‐2 antibodies. They all had a positive oro/nasopharyngeal swab reverse transcription‐polymerase chain reaction result. Assays used were a chemiluminescent assay measuring SARS‐CoV‐2 specific IgM and IgG (S + N) and an ELISA, measuring specific IgG (S1) and IgA antibodies against SARS‐CoV‐2. Among the 30 patients, eight were positive for IgA, seven were positive for IgG (N + S), and two for IgG (S1), at the first point (5‐7 days from the onset of symptoms). The IgA antibodies mean values at the second (9‐13 days) and third (21‐25 days) time points were even more than twice as high as IgG assays. The agreement between the two IgG assays was moderate (Cohen's K = 0.59; SE = 0.13). The inclusion of the IgA antibodies determination among serological tests of the COVID‐19 diagnostic is recommended. IgA antibodies may help to close the serological gap of the COVID‐19. Variations among anti‐SARS‐CoV‐2 IgG assays should be considered in the interpretation of results. Highlights: The inclusion of SARS‐CoV‐2 IgA antibodies may increase the diagnostic sensitivity of the serological tests for COVID‐19The early appearance and high concentrations of SARS‐CoV‐2 IgA antibodies make them good potential markers for identifying COVID‐19 patients.Variations of anti‐SARS‐CoV‐2 IgG assays exist. [ABSTRACT FROM AUTHOR]

We report the case of a 64-year-old man who presented with subacute memory, balance impairment, behavioral and mood changes, and epileptic seizures. Magnetic resonance imaging (MRI) showed bilateral hippocampal abnormalities. Brain [18F]-FDG fluorodeoxyglucose positron emission tomography (PET) revealed hypometabolism in both the temporal lobe as well as in the left insular and parietal regions. The clinical and neuroradiological picture and the detection of anti-CASPR2 antibodies in serum oriented the diagnosis towards autoimmune limbic encephalitis. Intravenous high-dose steroid and immunoglobulin treatments were ineffective. We did not use rituximab for the presence of antibodies to HbcAg positivity. Tocilizumab given intravenously 8 mg/kg once a month for six months and then subcutaneously 162 mg every week for six months resulted in clinical and neuroradiological improvement. These data support the efficacy of tocilizumab in autoimmune limbic encephalitis associated with anti-CASPR2 antibodies, which has been sporadically reported in the literature. [ABSTRACT FROM AUTHOR]

In the present study, we evaluated two novel technologies, the chemiluminescent immunoassay (CIA) QUANTA Flash on BIO-FLASH (Inova Diagnostics, San Diego, CA, USA) and the addressable laser bead immunoassay (ALBIA) on BioPlex™ 2200 (Bio-Rad, Hercules, CA, USA) for the detection of anti-cardiolipin IgG/IgM (aCL) and anti-β2–glycoprotein IgG/IgM (aβ2GPI) antibodies. The study was performed on 134 samples from consecutive patients (59 males and 75 females, mean age 54 ± 10 years) who consulted a rheumatologist because thrombosis and/or pregnancy complications were present or another immunological disease (Sjogren's syndrome, inflammatory arthritis). Fourteen patients of the total fulfilled 25the Sydney criteria for APS and for these patients previous results of aPLs were available. Sera were tested for aCL and aβ2GPI of IgG and IgM isotypes using CIA (BIO-FLASH) and ALBIA (BioPlex™ 2200). Overall agreement between CIA and ALBIA ranged from 88.1% (aCL IgG) to 97.8% (aβ2GPI IgG). Cohen's kappa coefficient ranged from 0.53 to 0.91, implying moderate to almost perfect agreement. Almost perfect agreement was found between BioPlex™ 2200 and BIO-FLASH aβ2GPI IgG and aCL IgM with Cohen's kappa of 0.91 and 0.88, respectively. On the other hand, moderate agreement was found between BioPlex™ 2200 and BIO-FLASH aCL IgG and β2GPI IgM assays with Cohen's kappa of 0.57 and 0.53, respectively. The two novel technologies look promising and comparable but further studies with larger cohorts are needed to contribute to the better understanding of the new aPLs antibodies assays performance. [ABSTRACT FROM AUTHOR]

Background: The dense fine speckled (DFS) is one of the most common patterns that can be observed as a result of the anti-nuclear antibodies (ANA) test on HEp-2 cells and is mostly caused by antibodies to DFS70 as the main antigenic target. As was recently demonstrated, isolated anti-DFS70 positivity can be used as an aid in the exclusion of ANA associated rheumatic diseases (AARD) due to the opportunity to better interpret unexplained positive IIF ANA results. Methods: Our study included 333 subjects with AARD, 51 undifferentiated connective tissue disease (UCTD) patients, 235 disease controls and 149 healthy blood donors from an Italian cohort. All samples were tested for anti-DFS70 and anti-ENA antibodies using QUANTA Flash assays (Inova Diagnostics, San Diego, CA, USA). Results: No differences in the prevalence of anti-DFS70 antibodies were seen among AARD, non-AARD and UCTD (2.1% [7/333] vs. 2.3% [9/384] vs. 5.9% [3/51], respectively; p-value = 0.188). AARD patients positive for anti-DFS70 antibodies showed in all cases an accompanying anti-ENA specificity. In contrast, monospecific anti-DFS70 antibodies showed a significantly different distribution with a clear trend across the main groups (AARD vs. non-AARD vs. UCTD: 0% [0/7] vs. 22% [2/9] vs. 100% [3/3], p = 0.007). Anti-DFS70 antibody levels among AARD, non-AARD and UCTD patients were not significantly different (p = 0.094). Within the anti-DFS70 antibody positive cases, AARD cohort showed a higher variability (median [min–max]: 3.2 [3.2–450.8] CU) compared to non-AARD (median [min–max]: 3.2 [3.2–75.7] CU) and UCTD patients (median [min–max]: 3.2 [3.2–59.0] CU). Conclusions: Our preliminary data showed a similar frequency of anti-DFS70 antibodies in AARD, UCTD and non-AARD cohorts. Monospecificity of anti-DFS70 antibodies but not their mere presence is the key element in the diagnostic algorithm. Mono-specific anti-DFS70 antibodies might be a helpful biomarker to discriminate individuals with AARD from non-AARD presenting with a positive ANA. [ABSTRACT FROM AUTHOR]

Background: Isolated antibodies to DFS70 have been described in healthy individuals and are rarely found in patients with antinuclear antibody-associated autoimmune rheumatic diseases (AARD). However, no data is available on geographic differences in the prevalence of anti-DFS70 antibodies. We aimed to study the prevalence of anti-DFS70 antibodies in blood donor samples from several countries representing various ethnical backgrounds and geographic regions in the world. Methods: Sera from apparently healthy blood donors (n≥300 per site) were collected in seven countries (USA, Italy, Spain, Germany, UK, Belgium and Brazil). All samples (n=2628) were tested for anti-DFS70 antibodies by QUANTA Flash DFS70 (Inova Diagnostics, Inc., San Diego, CA, USA). Results: The prevalence of anti-DFS70 antibodies varied from 4/321 (1.2%, Italy) to 42/497 (8.5%, USA). Consequently, the prevalence of the antibodies was significantly higher in USA compared to all other countries (p<0.05). In addition, the prevalence in the combined cohort (all sites) was higher in young blood donors (<35 years; 5.0% vs. 2.7%; p=0.0017) and among females (4.5% vs. 3.0%; p=0.0446). However, when cohorts from different countries were corrected for age and gender, no significant difference between the countries were found. Conclusions: This is the first study to analyze the prevalence of anti-DFS70 antibodies in different geographic areas using a standardized assay. Our findings show that the antibodies are most prevalent in young females. [ABSTRACT FROM AUTHOR]

Introduction: The aim of this study was to investigate the correlation between human leukocyte antigen (HLA) haplotypes and the development of antidrug antibodies (ADAs) in a cohort of patients with rheumatic diseases. Patients and methods: We evaluated the presence of ADAs in 248 patients with inflammatory rheumatic diseases after 6 months of treatment with anti-TNF drugs: 26 patients were treated with infliximab (IFX; three with rheumatoid arthritis [RA], 13 with ankylosing spondylitis [AS], 10 with psoriatic arthritis [PsA]); 83 treated with adalimumab (ADA; 24 with RA, 36 with AS, 23 with PsA); 88 treated with etanercept (ETA; 35 with RA, 27 with AS, 26 with PsA); 32 treated with certolizumab (CERT; 25 with RA, two with AS, five with PsA); and 19 treated with golimumab (GOL; three with RA, seven with AS, nine with PsA). Serum drug and ADA levels were determined using Lisa-Tracker Duo, the ADA-positive samples underwent an inhibition test, and the true-positive samples underwent genetic HLA typing. To have a homogeneous control population, we also performed genetic HLA typing of 11 ADA-negative patients. Results: After inhibition test, the frequency of ADAs was 2/26 patients treated with IFX (7.69%), 4/83 treated with ADA (4.81%), 0/88 treated with ETA (0%), 4/32 treated with CERT (12.5%), and 1/19 treated with GOL (5.26%). The frequency of HLA alleles in the examined patients was HLA-DRβ-11 0.636, HLA-DQ-03 0.636, and HLA-DQ-05 0.727. The estimated relative risks between the ADA-positive patients and the ADA-negative patients were HLA-DRβ-11 2.528 (95% CI 0.336-19.036), HLA-DQ-03 1.750 (95% CI 0.289-10.581), and HLA-DQ-05 2.424 (95% CI 0.308-15.449). Conclusion: This is the first study that shows an association between HLA and genetic factors associated with the occurrence of ADAs in patients with rheumatic diseases, but the number of samples is too small to draw any definite conclusion. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the real-life immunogenicity of anti-drug antibodies, drug levels, and disease activity in an Italian cohort of rheumatoid arthritis patients treated with tocilizumab (TCZ). We evaluated 126 TCZ-treated patients with rheumatoid arthritis (16 males and 110 females; mean age 59±12 years, range 26-83; mean disease duration 11±5 years) with inadequate 12-week response to any synthetic and biological disease-modifying anti-rheumatic drugs, in a retrospective analysis. One-hundred and seven patients were treated with methotrexate mean dose 12.6±1.3 mg/week in combination with TCZ, 13 received TCZ monotherapy, and six received leflunomide 20 mg/day plus TCZ; all patients were treated with prednisone mean dose 6.4±1.2 mg/day. They had a 28-joint Disease Activity Score (DAS28) of >3.2, an erythrocyte sedimentation rate (ESR) of >30 mm/hour, and CRP levels of <1.0 mg/dL. We evaluated at baseline and after 6 months of treatment: DAS28; rheumatoid factor (RF) IgM, IgA, and IgG; anti-citrullinated peptide antibody; ESR; CRP; TNF-α; and IL-6. TCZ and anti-TCZ antibodies were detected using LISA-TRACKER Duo TCZ. TCZ levels of <10 µg/mL were considered low and >10 µg/mL high. After 6 months of treatment only one patient was positive for anti-TCZ antibodies. There were correlations between DAS28, ESR, and CRP and IL-6 levels in all patients. Comparison of the 84 patients with TCZ levels of <10 µg/mL and the 42 with TCZ levels of >10 µg/mL showed the following differences: DAS28: 3.09±1.32 vs 2.78±1.32, P=0.0005; ESR: 27±14.8 vs 14±12 mm/hour, P=0.0001; CRP: 1.47±1.05 vs 0.65±0.80 mg/dL, P=0.0086; TNF-α: 10.2±1.2 vs 9.9±1.1 pg/mL, P=0.999; IL-6: 3.65±4.75 vs 3.62±4.41 pg/mL, P=0.97; anti-citrullinated peptide antibody: 85.2±93.7 vs 86.7±90.3 IU/mL, P=0.94; RF IgM: 72.4±62.7 vs 68.3±61.6 IU/mL, P=0.754; RF IgA: 41.7±36.4 vs 47.8±42.1 U/mL, P=0.449; and RF IgG: 46.4±46.1 vs 59.3±58.2 U/mL, P=0.212. These findings show that the occurrence of anti-drug antibodies against TCZ is very rare and that there are statistically significant correlations between TCZ levels of >10 µg/mL and ESR, CRP levels, and DAS28. [ABSTRACT FROM AUTHOR]

Although anti-TNF drugs have changed the clinical course of rheumatoid arthritis (RA), survival rates and resistance-to-therapy data confirm that about 30% of RA patients fail to respond. The aim of this study was to evaluate the correlations between the development of antidrug antibodies, specific IgG4 antibodies against TNF inhibitors, and resistance to therapy in RA patients. This retrospective study involved 129 patients with established RA naïve to biological agents (98 females and 32 males, mean age 56.7±12.3 years, disease duration 6.3±1.2 years, baseline Disease Activity Score [DAS]-28 3.2-5.6) who received treatment with anti-TNF agents after the failure of conventional disease-modifying antirheumatic drugs (32 received infliximab [IFX], 58 etanercept [ETN], and 39 adalimumab [ADA]). After 6 months of treatment, the patients were classified as being in remission (DAS28 <2.6), having low disease activity (LDA; DAS28 2.6-3.2), or not responding (NR: DAS28 >3.2). The patients were also tested for serum antidrug antibodies and IgG4 antibodies against TNF inhibitors. After 24 weeks of treatment, 38% of the ETN-treated patients and 28% of those treated with ADA had injection-site reactions; the rate of systemic reactions in the IFX group was 25%. The differences among the three groups were not statistically significant (P=0.382; ETN versus ADA P=0.319). The percentages of patients with adverse events stratified by drug response were: LDA 8% and NR 18% in the ADA group; in remission 3%, LDA 22%, and NR 10% in the ETN group; and LDA 6% and NR 16% in the IFX group (P=0.051). The percentages of patients with antidrug antibodies were: ADA 33.3%, ETN 11.5%, and IFX 10.3% (P=0.025; ADA versus ETN P=0.015). The percentages of patients with IgG4 antibodies were: ADA 6%, ETN 13%, and IFX 26% (P=0.017; ADA versus ETN P=0.437). Associations between antidrug antibodies, specific IgG4 antibodies, and adverse reactions were not significant for any of the three drugs. IgG4 levels were higher in the ADA group than in the other two groups, and higher in the patients with worse DAS28 (NR) and in those experiencing adverse events. These data suggest a possible association between IgG4 levels and worse DAS28 (r2=5.8%, P=0.011). The presence of specific IgG4 antibodies against TNF blockers in patients with RA might affect the drugs' activity. Patients with injection-site reactions and IgG4 against ETN may show a decreased response. [ABSTRACT FROM AUTHOR]

Introduction. The objective of the present study was to compare QUANTA Flash dsDNA, a chemiluminescent immunoassay (CIA) on the BIO-FLASH, a rapid-response chemiluminescent analyzer, to three other anti-dsDNA antibody assays and to Crithidia luciliae indirect immunofluorescence test (CLIFT). Methods. In the first part of the study, 161 samples, 61 from patients suffering from systemic lupus erythematosus (SLE) and 100 from a disease control group, were tested by QUANTA Flash dsDNA CIA, QUANTA Lite dsDNA SC ELISA, BioPlex 2200 multiplex flow immunoassay (MFI), ImmuLisa dsDNA ELISA, and NOVA Lite CLIFT. A second cohort of 69 SLE patients was then tested by QUANTA Flash dsDNA and CLIFT to expand the study. Results. The overall qualitative agreements varied between 77.0% (NOVA Lite CLIFT versus QUANTA Lite) and 89.4% (ImmuLisa versus NOVA Lite CLIFT). The clinical sensitivities for the anti-dsDNA antibody tests varied from 8.2% (NOVA Lite CLIFT) to 54.1% (QUANTA Lite), while the clinical specificities varied from 88.0% (BioPlex 2200) to 100.0% (NOVA Lite CLIFT). Good correlation was found between QUANTA Flash dsDNA and NOVA Lite CLIFT. Conclusion. Significant variations among dsDNA methods were observed. QUANTA Flash dsDNA provides a good combination of sensitivity and specificity for the diagnosis of SLE and good agreement to CLIFT. [ABSTRACT FROM AUTHOR]

Autoantibodies against extractable nuclear antigens (ENA) play a pivotal role in the diagnosis and classification of systemic autoimmune rheumatic diseases (SARD). In recent years, newly developed methods have enabled the simultaneous and quantitative detection of multiple anti-ENA reactivities. However, data regarding the comparability of results obtained using different technologies across different platforms are scarce. In this study we compared eight different immunoassays, commonly used in current laboratory practice for detection of anti-ENA antibodies. Sixty patients suffering from different SARD, 10 inflammatory arthritis patients (disease controls) and 10 healthy blood donors were included in this comparative study. Sera were collected in 15 centers belonging to the Study Group on Autoimmune Diseases of the Italian Society of Clinical Pathology and Laboratory Medicine. We evaluated the analytical sensitivity, specificity and diagnostic accuracy of each method for antibodies to Sm, RNP, Ro60, Ro52, Scl70, CENP-B and Jo1. Cohen's kappa was used to analyze the agreement among methods. Average agreement among methods was 0.82, ranging from substantial (k = 0.72) to almost perfect (k = 0.92). However, while the specificity was very good for all methods, some differences emerged regarding the analytical sensitivity. Diagnostic performance of current technologies for anti-ENA antibody detection showed good comparability. However, as some differences exist among methods, laboratory scientists and clinicians must be aware of the diagnostic accuracy of the testing method in use. • Antibodies to ENA are important in the diagnosis of autoimmune rheumatic diseases. • Many different immunological methods are available to the clinical laboratory. • Diagnostic performance of current immunoassays show good comparability. • Though agreement among assays is good, differences exist in diagnostic accuracy. • Clinicians and laboratory scientists should be aware of these differences. [ABSTRACT FROM AUTHOR]

ACPA (anti-citrullinated protein antibody) tests are today systematically added to clinical and radiological investigations when diagnosing rheumatoid arthritis (RA), and the inclusion of ACPA positivity in the new 2010 RA criteria underlines their importance. The aim of this study was to determine the sensitivity and specificity of different ACPA assays and IgA, IgG and IgM isotypes of rheumatoid factor (RF) in a cohort of patients with early RA in order to assess the value of combining the tests. The serum samples were obtained from 46 RA patients, 80 patients with systemic rheumatic disease, and 20 blood donors. ACPAs were measured using five different commercial kits. The receiver operating characteristic (ROC) curves of the anti-ACPA tests had area under the curve (AUC) values of 0.60-0.83. The diagnostic accuracy of the Bio-Rad multiplex flow immunoassay, a new technology for ACPA testing, was very similar to that of the other widely used commercial immunoassays. The EliA CCP-Phadia test was the most specific, and had the best positive likelihood ratio and positive predictive values, whereas the anti-CCP Inova 3.1 test was the most sensitive, and had the best negative likelihood ratio and negative predictive values. The best combination to use for early RA screening was an ACPA test together with IgM and IgA RF. [ABSTRACT FROM AUTHOR]

The serological screening for celiac disease (CD) is currently based on the detection of anti-transglutaminase (tTG) IgA antibodies, subsequently confirmed by positive endomysial antibodies (EMA). When an anti-tTG IgA positive/EMA IgA negative result occurs, it can be due either to the lower sensitivity of the EMA test or to the lower specificity of the anti-tTG test. This study aimed at verifying how variation in analytical specificity among different anti-tTG methods could account for this discrepancy. A total of 130 consecutive anti-tTG IgA positive/EMA negative samples were collected from the local screening routine and tested using five anti-tTG IgA commercial assays: two chemiluminescence methods, one fluoroimmunoenzymatic method, one immunoenzymatic method and one multiplex flow immunoassay method. Twenty three/130 (17.7%) patients were diagnosed with CD. In the other 107 cases a diagnosis of CD was not confirmed. The overall agreement among the five anti-tTG methods ranged from 28.5% to 77.7%. CD condition was more likely linked to the positivity of more than one anti-tTG IgA assay (monopositive = 2.5%, positive with ≥ three methods = 29.5%; p = 0.0004), but it was not related to anti-tTG IgA antibody levels (either positive or borderline; p = 0.5). Patients with positive anti-tTG/negative EMA have a low probability of being affected by CD. Given the high variability among methods to measure anti-tTG IgA antibodies, anti-tTG-positive/EMA-negative result must be considered with extreme caution. It is advisable that the laboratory report comments on any discordant results, suggesting to consider the data in the proper clinical context and to refer the patient to a CD reference center for prolonged follow up. [ABSTRACT FROM AUTHOR]

• IVIg may be replaced by SCIg in the maintenance therapy of anti-HMGCR myopathy. • SCIg induced a sustained clinical stability in anti-HMGCR myopathy. • Anti-HMGCR antibodies are an important marker for the prognosis and response to therapy. We describe the clinical response to long-term subcutaneous immunoglobulins (SCIg) in anti-3‑hydroxy-3-methyl-glutaryl-coenzyme-A-reductase (anti-HMCGR) myopathy previously treated with intravenous immunoglobulins (IVIg). We collected data from patients affected by anti-HMGCR myopathy, switched from IVIg to SCIg therapy, after achieving clinical stabilization. The Medical Research Council sum score, creatine kinase (CK) levels, and anti-HMGCR antibodies were used to assess the response. We identified three patients with anti-HMGCR myopathy treated with SCIg with a favourable clinical course, allowing the maintenance of clinical stability, the reduction or suspension of steroids therapy and in two of them a complete CK normalization. Finally, anti-HMGCR antibodies tested in all patients after 12 months from SCIg starting, showed a global decrease. SCIg represent an useful alternative to long-term IVIg as already well known in several autoimmune neuromuscular disorders and inflammatory myopathies with advantages of lower side effects and home self-administration. [ABSTRACT FROM AUTHOR]

Objective To evaluate two new diagnostic methods for the identification of anti-DFS70 antibodies in samples showing a DFS70-staining pattern by indirect immunofluorescence (IIF). Methods We studied 731 patients: 576 were collected consecutively among those that in the ANA test on HEp-2 cells had produced a DFS70 fluorescence pattern and 155 were a consecutive series of patients sent by referring physicians for routine ANA testing. As controls we studied 50 patients with autoimmune diseases and 120 patients with active infectious disease. All 731 sera were assayed for anti-DFS70 antibodies by a specific chemoluminescence assay (CLIA); 70 randomly selected IIF-positive sera and 35 samples from patients with autoimmune diseases were studied by inhibition tests using the HEp-2 Select method. Results Assays performed with the CLIA-DFS70 method were positive in 30.4% of the samples presenting a DFS70 pattern by IIF, in 1.3% of the routine ANA sera, in 1.6% of the infectious sera and in none of the 50 autoimmune controls. However, as the IIF-DFS70 positive group included 106 patients with systemic autoimmune rheumatic diseases (SARD), 11 of which were DFS70 positive by CLIA, the prevalence of DFS70 antibodies in SARD was 7.5 %. The ANA test performed after the use of HEp-2 Select showed an inhibition in 95.7% of the sera. No change in fluorescence intensity and pattern morphology between the native sera and the same sera tested with the solution containing the DFS70 antigen was observed in the 35 samples from patients with autoimmune diseases. Conclusions To avoid misinterpretation of ANA pattern and consequent diagnostic errors, confirmation of the DFS70-IIF pattern by CLIA or other specific methods is mandatory before reporting the presence of anti-DFS70 antibodies. The HEp-2 Select test in most cases eliminates the interference by anti-DFS70 antibodies and avoids the possible reporting of false positive results. [ABSTRACT FROM AUTHOR]