Brief Papers
Distinct dermatomyositis populations are detected with different autoantibody assay platforms
D.F. Fiorentino1, L. Gutierrez-Alamillo2, D. Hines3, Q. Yang4, L. Casciola-Rosen5
- Stanford University School of Medicine, Department of Dermatology, Stanford, CA, USA. fiorentino@stanford.edu
- Johns Hopkins University School of Medicine, Division of Rheumatology, Baltimore, MD, USA.
- Johns Hopkins University School of Medicine, Division of Rheumatology, Baltimore, MD, USA.
- Johns Hopkins University School of Medicine, Division of Rheumatology, Baltimore, MD, USA.
- Johns Hopkins University School of Medicine, Division of Rheumatology, Baltimore, MD, USA.
CER12171
2019 Vol.37, N°6
PI 1048, PF 1051
Brief Papers
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PMID: 31376258 [PubMed]
Received: 17/02/2019
Accepted : 20/05/2019
In Press: 19/07/2019
Published: 02/12/2019
Abstract
OBJECTIVES:
To compare autoantibody-defined dermatomyositis sub-populations using immunoprecipitation-based assays, a commercially available line immunoblot assay and alternate commercial ELISA assays.
METHODS:
Banked plasma from 261 carefully phenotyped dermatomyositis patients was studied. Immunoprecipitation-based assays were used to detect antibodies against Mi2, TIF1-γ MDA5, NXP2, SAE1 and PM-Scl, while anti-Jo1 antibodies were assayed using ELISA. These data were compared with that obtained using a commercial line immunoblot, and, additionally, for Mi2, TIF1-γ, MDA5, commercially available ELISA kits. Test agreement was measured using Cohen’s kappa statistic, and phenotypic differences between differentially identified groups are described.
RESULTS:
Line immunoblot, immunoprecipitation, and ELISA detected increasingly larger nested pools of anti-TIF1-γ samples, with increasing frequency of concurrent anti-Mi2 reactivity and decreasing incidence of malignancy. Line immunoblot and immunoprecipitation showed fair concordance for identifying anti-NXP2 antibodies (Cohen’s kappa=0.71) but very good agreement for identifying antibodies against Mi2, MDA5, and SAE1 (Cohen’s κ=0.9, 0.94, 0.88, respectively). Anti-PM-Scl results showed moderate agreement (Cohen’s κ=0.48) between immunoblot and immunoprecipitation.
CONCLUSIONS:
Our results demonstrate that for some specificities, especially anti-TIF1-γ, antibody results obtained using different assay platforms vary, and identify significantly different patient populations. These findings highlight the need for standard adoption of carefully validated platforms to detect dermatomyositis autoantibodies.
