Clinical Utility of an Enzyme-Linked Immunosorbent Assay for Detecting Anti-Melanoma Differentiation-Associated Gene 5 Autoantibodies.
Autoantibodies to melanoma differentiation-associated gene 5 (MDA5) are specifically expressed in patients with dermatomyositis (DM) and are associated with a subset of DM patients with rapidly progressive interstitial lung disease (RP-ILD). Here, we examined the clinical utility of a newly developed enzyme-linked immunosorbent assay (ELISA) system for detecting these antibodies.



Here we developed an improved ELISA for detecting anti-MDA5 antibodies. We then performed a multicenter clinical study involving 8 medical centers and enrolled 242 adult patients with polymyositis (PM)/DM, 190 with non-PM/DM connective tissue disease (CTD), 154 with idiopathic interstitial pneumonia (IIP), and 123 healthy controls. Anti-MDA5 antibodies in the patients' serum samples were quantified using our newly developed ELISA, and the results were compared to those obtained using the gold-standard immunoprecipitation (IP) assay. In addition, correlations between the ELISA-quantified anti-MDA5 antibodies and clinical characteristics were evaluated.



In patients with PM/DM, the anti-MDA5 antibody measurements obtained from the ELISA and IP assay were highly concordant; the ELISA exhibited an analytical sensitivity of 98.2%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 99.5% (compared to the IP assay). Anti-MDA5 antibodies were detected in 22.7% of the DM patients, but not in any of the patients with PM, non-PM/DM CTD, or IIP. Clinically amyopathic DM, RP-ILD, arthritis, and fever were more prevalent in DM patients who were anti-MDA5 antibody-positive than in those who were antibody-negative (P ≤ 0.0002 for all comparisons). In addition, anti-MDA5 antibody-positive patients with RP-ILD exhibited higher antibody levels than those without RP-ILD (P = 0.006).



Our newly developed ELISA can detect anti-MDA5 antibodies as efficiently as the gold standard IP assay and has the potential to facilitate the routine clinical measurement of anti-MDA5 antibodies in patients who suspected to have DM.
Division of Rheumatology, Department of Internal Medicine, Tokai University, School of Medicine, Isehara 259-1193, Japan.
Shinji
S
Sato
Medical and Biological Laboratories, Nagoya 460-0008, Japan.
Akihiro
A
Murakami
Medical and Biological Laboratories, Nagoya 460-0008, Japan.
Akiko
A
Kuwajima
Department of Dermatology, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa 920-8641, Japan.
Kazuhiko
K
Takehara
Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan.
Tsuneyo
T
Mimori
Unit of Translational Medicine, Department of Immunology and Rheumatology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8501, Japan.
Atsushi
A
Kawakami
Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan.
Michiaki
M
Mishima
Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan.
Takafumi
T
Suda
Department of Dermatology, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan.
Mariko
M
Seishima
Department of Dermatology, Faculty of Medicine, Tsukuba University, Tsukuba 305-8575, Japan.
Manabu
M
Fujimoto
Department of Allergy and Rheumatology, Nippon Medical School Graduate School of Medicine, Tokyo 113-8603, Japan.
Masataka
M
Kuwana
D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood*; D016022:Case-Control Studies; D003240:Connective Tissue Diseases / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D003882:Dermatomyositis / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D003937:Diagnosis, Differential; D004797:Enzyme-Linked Immunosorbent Assay / Q000592:standards*; D005260:Female; D015870:Gene Expression; D006801:Humans; D054988:Idiopathic Interstitial Pneumonias / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D047468:Immunoprecipitation; D000072640:Interferon-Induced Helicase, IFIH1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D017285:Polymyositis / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D012680:Sensitivity and Specificity
D001323:Autoantibodies; C452815:IFIH1 protein, human; D000072640:Interferon-Induced Helicase, IFIH1