Detection of myositis-specific antibodies: additional notes

Infantino, María; Manfredi, Mariangela; Grossi, Valentina; Benucci, Maurizio

doi:10.1136/annrheumdis-2018-213320

Cited by 4 publications

(5 citation statements)

References 7 publications

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“…The diagnostic use of MSA/MAA LIAs in this setting is unclear and has not been assessed so far. 7,8 This study aims to investigate the use and diagnostic value of MSA/MAA LIA in a large cohort of patients.…”

Section: Introductionmentioning

confidence: 99%

The use and diagnostic value of testing myositis-specific and myositis-associated autoantibodies by line immuno-assay: a retrospective study

Lackner

Tiefenthaler

Mirzayeva

et al. 2020

Therapeutic Advances in Musculoskeletal

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Aims: Line immune-assays (LIA) for the detection of myositis-specific antibodies (MSA) are used widely for characterization of idiopathic inflammatory myopathies (IIM). Their current use and significance for the diagnosis of IIM remains unclear. Methods: In this retrospective analysis, we retrieved clinical diagnoses of patients tested for MSA and myositis-associated antibodies (MAA) Jo-1, Mi-2α, Mi-2β, TIF1γ, SRP, MDA-5, NXP-2, SAE, PL-7, PL-12, EJ, OJ, PM-Scl100, PM-Scl75 and Ku. We calculated clinical specificity, clinical sensitivity, negative- and positive predictive values (PPV) as well as positive and negative likelihood ratios. Results: In total, we analyzed 3167 samples. After exclusion of repeated measurements and patients with insufficient clinical information, data of 1118 patients were available for analysis. A total of 242 patients tested positive for at least one antibody, of which 45 patients had a diagnosis of IIM; 25 IIM patients were negative for all MSA/MAA. Clinical specificity of MSA/MAA for the diagnosis of IIM ranged between 94.2% and 99.9%. Clinical sensitivity and PPV across all antibodies tested ranged from 0.0% to 12.9% and 0.0% to 72.7%, respectively. Conclusion: In clinical practice MSA/MAA are used widely for diagnostic work-up of IIM, resulting in a low pre-test probability. Clinicians should be aware that PPVs for most MSA/MAA are low.

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Section: Introductionmentioning

confidence: 99%

The use and diagnostic value of testing myositis-specific and myositis-associated autoantibodies by line immuno-assay: a retrospective study

Lackner

Tiefenthaler

Mirzayeva

et al. 2020

Therapeutic Advances in Musculoskeletal

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“…It has been already demonstrated that multiple testing, whereas increasing efficiency could also increase false-positive results. Several reports described how the agreement between commercial assay and IP may be influenced by the rarity of the autoantibody or by the antigen specificity and no conclusive data are currently available [16][17][18][19][20][21][22][23][24][25][26]44]. In 2019, Fiorentino et al compared results from LB and IP in DM patients, and only a fair concordance was found for NXP2 specificity [26] differently from the moderate concordance shown by a previous study [17].…”

Section: Discussionmentioning

confidence: 99%

“…Historically, these clinical associations have been described when the immunoprecipitation (IP) technique was used for anti-NXP2 detection. Commercial line/dot immunoassays have been released in the last few years; to date, the performance of these tests in IIM is still under discussion [16][17][18][19][20][21][22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

An Italian Multicenter Study on Anti-NXP2 Antibodies: Clinical and Serological Associations

Fredi

Cavazzana

Ceribelli

et al. 2022

Clinic Rev Allerg Immunol

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The identification of anti-NXP2 antibodies is considered a serological marker of dermatomyositis (DM), with calcinosis, severe myositis and, in some reports, with cancer. Historically, these associations with anti-NXP2 antibodies have been detected by immunoprecipitation (IP), but in the last few years commercial immunoblotting assays have been released. The aim of this collaborative project was to analyse the clinical features associated to anti-NXP2 antibodies, both with commercial line blot (LB) and IP. Myositis-specific and myositis-associated autoantibodies were detected in single centres by commercial line blot (LB); available sera were evaluated in a single centre by protein and RNA immunoprecipitation (IP), and IP-Western blot. Sixty patients anti-NXP2+ (NXP2+) positive by LB were compared with 211 patients anti-NXP2 negative with idiopathic inflammatory myositis (IIM). NXP2+ showed a younger age at IIM onset (p = 0.0014), more frequent diagnosis of dermatomyositis (p = 0.026) and inclusion-body myositis (p = 0.009), and lower rate of anti-synthetase syndrome (p < 0.0001). As for clinical features, NXP2+ more frequently develop specific skin manifestations and less frequently features related with overlap myositis and anti-synthetase syndrome. IP confirmed NXP2 positivity in 31 of 52 available sera (62%). Most clinical associations were confirmed comparing NXP2 LB+/IP+ versus NXP2-negative myositis, with the following exceptions: inclusion-body myositis diagnosis was not detected, whilst dysphagia and myositis were found more frequently in NXP2 LB+/IP+ patients. The 21 LB+ /IP-myositis patients did not show differences in clinical features when compared with the NXP2-myositis patients and more frequently displayed multiple positivity at LB. Risk of developing cancer-associated myositis was similar between NXP2-positive and NXP2-negative myositis patients, either when detected by LB or IP. Protein-IP confirmed NXP2 antibodies in nearly 60% of sera positive for the same specificity with commercial assay. Double-positive cases rarely occurred in myositis patients with a clinical diagnosis other than dermatomyositis. Patients only positive by LB (LB+/IP−) did not display clinical features typical of NXP2. NXP2 positivity by LB should be confirmed by other methods in order to correctly diagnose and characterize patients affected by idiopathic inflammatory myositis.

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“…Some authors already suggested minimal actions to improve the quality of the assays such as the integration of quality control procedures (e.g. participation in external quality control programs and the inclusion of internal quality control material) [ 57 , 58 ], adapting the cut-off values [ 38 , 45 , 57 , 59 ] and correlating with the IFA pattern [ 40 , 59 ]. Automated reading of the line/dot blot is also of utmost importance to improve reproducibility.…”

Section: Reliability Of the Different Methods And/or Assaysmentioning

confidence: 99%

Positioning of myositis-specific and associated autoantibody (MSA/MAA) testing in disease criteria and routine diagnostic work-up

Bonroy

Piette

Allenbach

et al. 2022

Journal of Translational Autoimmunity

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Detection of myositis-specific antibodies: additional notes

Cited by 4 publications

References 7 publications

The use and diagnostic value of testing myositis-specific and myositis-associated autoantibodies by line immuno-assay: a retrospective study

The use and diagnostic value of testing myositis-specific and myositis-associated autoantibodies by line immuno-assay: a retrospective study

An Italian Multicenter Study on Anti-NXP2 Antibodies: Clinical and Serological Associations

Positioning of myositis-specific and associated autoantibody (MSA/MAA) testing in disease criteria and routine diagnostic work-up

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