Background/Purpose: Dermatomyositis (DM) is an autoimmune inflammatory disease characterized by skin eruptions and myositis, which is occasionally complicated by interstitial lung disease (ILD) or concomitant malignancy. It has been recognized that myositis-specific autoantibodies (MSAs) are correlated with unique sets of clinical manifestations. Anti–transcriptional intermediary factor 1-γ (TIF1-γ) antibody is one of the most frequently detected MSAs both in juvenile and adult DM, and adult DM positive for anti-TIF1-γ have a markedly higher rate of malignancy. In Japan, an individual measurement of anti-TIF1-γ by enzyme-linked immunosorbent assay (ELISA) is now covered by insurance. However, little is known about clinical utility of quantitative ELISA index of anti-TIF1-γ in association with disease activity.

Methods: We studied 26 Japanese adult DM patients positive for anti-TIF1-γ antibody detected by ELISA, who had been under treatment in our department. All patients were confirmed negative for anti-Mi-2 antibody concomitantly measured by ELISA. Seventeen patients with anti-TIF1-γ antibody (65.4%) had concomitant malignancy which was defined by the diagnosis within 2 years before or after DM diagnosis. Sequential serum samples were obtained in 16 patients. Clinical utility of quantitative anti-TIF1-γ index was analyzed in association with patient’s characteristics and disease severity.

Results: Anti-TIF1-γ-positive patients frequently had facial erythema (84.6%) including heliotrope rash (73.0%), Gottron’s papules (69.2%), erythema of the trunk (61.5%), and dysphagia (46.2%). Three patients were classified as clinically amyopathic DM (11.1%) and 5 patients had ILD (18.5%). Although maximum levels of serum creatine kinase (CK) was significantly higher in patients with malignancy compared to those without (mean ± SD IU/L, 2494.1 ± 5326.9, 392.3 ± 423.3, respectively, P < 0.05), there was no significant difference on anti-TIF1-γ index between patients with and without malignancy (105.4 ± 38.0, 113.0 ± 39.2, respectively, P = 0.32). No positive correlation was found between levels of serum CK and anti-TIF1-γ (r = 0.32, P = 0.17). In sequential analysis (n=16), anti-TIF1-γ level in patients without malignancy was decreased by more than 30% or turned negative after treatment for DM. However, antibody titer tended to be sustained in patients with malignancy at stage IV. Interestingly, re-increase of antibody titer was observed at a recurrence of malignancy (n=1) or increase of DM activity (n=3). Two patients had completely succeeded treatments for their malignancy, then anti-TIF1-γ level turned negative as loss of DM activity.

Conclusion: Higher index of anti-TIF1-γ may not directly indicate the presence of malignancy or higher activity of DM. However, longitudinal change of anti-TIF1-γ index in individual patients may partially reflect activities both of DM and malignancy. Close monitoring may be suggested if patients have sustained antibody titer despite no malignancy and loss of DM activity.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-significance-of-serum-levels-of-anti-transcriptional-intermediary-factor-1-%ce%b3-antibody-in-patients-with-dermatomyositis/