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Berge M, Bertilsson L, Hultgren O, Hugosson S, Saber A. Qualitative and quantitative comparison of allergen component-specific to birch and grass analyzed by ImmunoCAP assay and Euroline immunoblot test. Eur Ann Allergy Clin Immunol 2023; 55:68-77. [PMID: 35029100 DOI: 10.23822/eurannaci.1764-1489.241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Summary Background.In the diagnostic work up of allergy, determining allergen component-specific immunoglobulin E (IgE) is important for diagnosis, prognosis and choice of treatment. The purpose of this study was to evaluate the performance of the immunoblotting assay (Euroline) in detection of IgE antibodies against timothy grass and birch pollen allergen components compared to fluorescent enzyme assay (ImmunoCAP, Phadia 250). Methods. A total of 128 serum samples from patients allergic to timothy grass and birch pollen were analysed. The levels of IgE antibodies to timothy grass and birch pollen were measured using Euroline DPA-Dx pollen 1 and ImmunoCAP assay. The two methods were then compared on binary (positive vs negative), semi-quantitative (IgE classes) and quantitative (concentration) levels. The two methods were also compared to results from skin prick testing. Results. The Euroline method showed a positive percentage agreement of 93% and negative percentage agreement of 94% with an overall accuracy of 94% when compared to ImmunoCAP. Kappa analysis showed moderate strength of agreement between the methods in determining IgE classes for 7/11 components tested. All components showed a positive correlation when analysed using Spearman's rank correlation. Conclusions. Overall, we found that there is good correlation between the Euroline and ImmunoCAP methods in measuring IgE sensitization.
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Affiliation(s)
- M Berge
- Department of Otolaryngology, Örebro University Hospital, Örebro, Sweden
| | - L Bertilsson
- Department of Laboratory Medicine, Örebro University Hospital, Örebro, Sweden
| | - O Hultgren
- Department Clinical Immunology and Transfusion Medicine, Faculty of Medicine and Health, Örebro University, Örebro, Sweden
| | - S Hugosson
- Deptartment of Otolaryngology, Örebro University Hospital, School of Medial Sciences, Faculty of Medicine and Health, Örebro University, Örebro, Sweden
| | - A Saber
- Deptartment of Otolaryngology, Örebro University Hospital, School of Medial Sciences, Faculty of Medicine and Health, Örebro University, Örebro, Sweden
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Casal-Dominguez M, Pinal-Fernandez I, Derfoul A, Graf R, Michelle H, Albayda J, Tiniakou E, Adler B, Danoff SK, Lloyd TE, Christoper-Stine L, Paik JJ, Mammen AL. The phenotype of myositis patients with anti-Ku autoantibodies. Semin Arthritis Rheum 2021; 51:728-734. [PMID: 34144382 DOI: 10.1016/j.semarthrit.2021.04.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 03/31/2021] [Accepted: 04/22/2021] [Indexed: 10/21/2022]
Abstract
OBJECTIVES To define the clinical features of anti-Ku-positive myositis patients and to determine the reliability of the Euroline assay to detect anti-Ku autoantibodies. METHODS Serum samples were screened for anti-Ku autoantibodies by Euroline and positive samples were confirmed by ELISA. The prevalence and severity of clinical features at onset and during follow-up in patients with anti-Ku-positive myositis were compared to those with dermatomyositis, immune-mediated necrotizing myopathy (IMNM), the antisynthetase syndrome (AS), inclusion body myositis (IBM), anti-U1-RNP-positive myositis, and anti-PM/Scl-positive myositis. RESULTS 72 (2.9%) of 2475 samples were anti-Ku positive by Euroline using the manufacturer's recommended cutoff of >15. Just 17 (23.6%) of these were confirmed by ELISA and considered anti-Ku-positive for the analysis. Comparators included 169 IMNM, 168 AS, 387 IBM, 20 anti-U1-RNP-positive, and 47 anti-PM/Scl-positive patients. Muscle weakness was a presenting feature in 38% of anti-Ku-positive patients; 81% developed weakness during follow-up. Anti-Ku-positive patients had increased distal weakness compared to the non-IBM comparators. Interstitial lung disease (ILD) was present in 19% of anti-Ku-positive patients at the first visit and eventually developed in 56% of them. Throughout the course of disease, Gottron's papules and/or heliotrope rashes were less common in anti-Ku-positive patients (19%) compared to those with dermatomyositis (94%) or anti-PM/Scl-positive myositis (89%). Anti-Ku-positive patients never developed calcinosis. CONCLUSIONS The phenotype of anti-Ku positive myositis is distinguished by distal weakness, frequent ILD, infrequent rash, and no calcinosis. When used according to the current manufacturer's instructions, the Euroline assay has a high false-positive rate for anti-Ku autoantibodies.
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Affiliation(s)
- Maria Casal-Dominguez
- Muscle Disease Unit, Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD USA; Johns Hopkins University School of Medicine, Baltimore, Maryland USA.
| | - Iago Pinal-Fernandez
- Muscle Disease Unit, Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD USA; Johns Hopkins University School of Medicine, Baltimore, Maryland USA; Faculty of Health Sciences and Faculty of Computer Science, Multimedia and Telecommunications, Universitat Oberta de Catalunya, Barcelona, Spain
| | - Assia Derfoul
- Muscle Disease Unit, Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD USA
| | - Rose Graf
- Muscle Disease Unit, Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD USA
| | - Harlan Michelle
- Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Jemima Albayda
- Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Eleni Tiniakou
- Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Brittany Adler
- Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Sonye K Danoff
- Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Thomas E Lloyd
- Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | | | - Julie J Paik
- Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Andrew L Mammen
- Muscle Disease Unit, Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD USA; Johns Hopkins University School of Medicine, Baltimore, Maryland USA.
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