TY - JOUR
T1 - The indirect immunofluorescence assay autoantibody profiles of myositis patients without known myositis-specific autoantibodies
AU - Casal-Dominguez, M.
AU - Pinal-Fernandez, I.
AU - Pak, K.
AU - Marin-Sanchez, A.
AU - Sanz-Martinez, M. T.
AU - Baucells, A.
AU - Hosono, Y.
AU - Christopher-Stine, L.
AU - Mammen, A. L.
N1 - Funding Information:
Funding: 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. We are also grateful to Dr Peter Buck, whose generous support made this work possible.
Publisher Copyright:
© Copyright CliniCal and ExpErimEntal rhEumatology 2021.
PY - 2021/5
Y1 - 2021/5
N2 - Objective The indirect immunofluorescence assay (IIFA) is used to screen for the presence of autoantibodies. Our objective was to determine the prevalence and clinical features of IIFA positive myositis patients without known myositis-specific autoantibodies (MSA). Methods Sera from healthy comparators (HC) and patients with dermatomyositis (DM), inclusion body myositis (IBM), and polymyositis (PM) with no detectable MSA were tested by IIFA on HEp-2 cells. The pattern of positivity was classified according to the International Consensus on Antinuclear Antibody Patterns. The prevalence and frequency of each IIFA pattern were compared between the different groups. Results Sera from 100 HC, 71 DM, 53 IBM, and 69 PM subjects were included in the study. The IIFA was positive in 35% HC compared to 66% DM (p<0.001), 49% IBM, and 64% (p<0.001) PM sera. Among IIFA positive sera, the staining was moderate or intense in 43% HC compared to 79% DM (p<0.001) but just 54% IBM, and 52% PM sera. IIFA positivity was predominantly nuclear in all groups (all >69%). The most common pattern in myositis patients was fine speckled with no differences between groups. In general, IIFA positive and negative DM patients showed similar clinical features and disease activity. Conclusion Half of MSA-negative DM patients have moderate/strong IIFA positivity, predominantly with a fine speckled pattern. In contrast, MSA-negative PM, IBM, and healthy comparators are more often weakly positive for IIFA. These findings suggest that unidentified autoantibodies are more likely to exist in DM patients than in the other myositis groups.
AB - Objective The indirect immunofluorescence assay (IIFA) is used to screen for the presence of autoantibodies. Our objective was to determine the prevalence and clinical features of IIFA positive myositis patients without known myositis-specific autoantibodies (MSA). Methods Sera from healthy comparators (HC) and patients with dermatomyositis (DM), inclusion body myositis (IBM), and polymyositis (PM) with no detectable MSA were tested by IIFA on HEp-2 cells. The pattern of positivity was classified according to the International Consensus on Antinuclear Antibody Patterns. The prevalence and frequency of each IIFA pattern were compared between the different groups. Results Sera from 100 HC, 71 DM, 53 IBM, and 69 PM subjects were included in the study. The IIFA was positive in 35% HC compared to 66% DM (p<0.001), 49% IBM, and 64% (p<0.001) PM sera. Among IIFA positive sera, the staining was moderate or intense in 43% HC compared to 79% DM (p<0.001) but just 54% IBM, and 52% PM sera. IIFA positivity was predominantly nuclear in all groups (all >69%). The most common pattern in myositis patients was fine speckled with no differences between groups. In general, IIFA positive and negative DM patients showed similar clinical features and disease activity. Conclusion Half of MSA-negative DM patients have moderate/strong IIFA positivity, predominantly with a fine speckled pattern. In contrast, MSA-negative PM, IBM, and healthy comparators are more often weakly positive for IIFA. These findings suggest that unidentified autoantibodies are more likely to exist in DM patients than in the other myositis groups.
KW - Autoimmune myopathies
KW - Immunofluorescence pattern
KW - Indirect immunofluorescence assay
KW - Myositis-specific autoantibodies
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M3 - Article
C2 - 32896249
AN - SCOPUS:85106480377
SN - 0392-856X
VL - 39
SP - 519
EP - 524
JO - Clinical and experimental rheumatology
JF - Clinical and experimental rheumatology
IS - 3
ER -