TY - JOUR
T1 - The phenotype of myositis patients with anti-Ku autoantibodies
AU - Casal-Dominguez, Maria
AU - Pinal-Fernandez, Iago
AU - Derfoul, Assia
AU - Graf, Rose
AU - Michelle, Harlan
AU - Albayda, Jemima
AU - Tiniakou, Eleni
AU - Adler, Brittany
AU - Danoff, Sonye K.
AU - Lloyd, Thomas E.
AU - Christoper-Stine, Lisa
AU - Paik, Julie J.
AU - Mammen, Andrew L.
N1 - Funding Information:
This research was supported by the Intramural Research Program of the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health (AR-041203). We are also grateful to Dr. Peter Buck, whose generous support made this work possible. IPF's research was supported by a Fellowship from the Myositis Association. JJP's research was supported by an award from the National Institutes of Health (K23-AR073927). We also want to acknowledge the Hopkins Rheumatic Diseases Research Core center, which is funded by the National Institutes of Health and the National Institute of Arthritis, Musculoskeletal and Skin Diseases grant P30-AR070254.
Publisher Copyright:
© 2021
PY - 2021/8
Y1 - 2021/8
N2 - 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.
AB - 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.
KW - Elisa
KW - Euroline
KW - Myositis
KW - anti-Ku
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U2 - 10.1016/j.semarthrit.2021.04.012
DO - 10.1016/j.semarthrit.2021.04.012
M3 - Article
C2 - 34144382
AN - SCOPUS:85107931614
SN - 0049-0172
VL - 51
SP - 728
EP - 734
JO - Seminars in Arthritis and Rheumatism
JF - Seminars in Arthritis and Rheumatism
IS - 4
ER -