Anti-TIF1γ antibody and the expression of TIF1γ in idiopathic inflammatory myopathies.

Objective: Anti-transcriptional intermediary factor 1 (TIF1) antibody is associated with idiopathic inflammatory myopathies (IIMs). The aim of this study was to investigate the expression of TIF1s in IIMs.

Method: TIF1α, β or γ expression in the skin and muscle of patients and controls was studied by immunohistochemistry. Serum myositis-specific autoantibodies were detected by immunoblot.

Results: TIF1α was expressed in the skin of most dermatomyositis (DM) patients but not in the controls (80% vs 0%, P < 0.001). TIF1β was expressed in all tissues of patients and controls. TIF1γ was expressed in the muscle of DM patients compared to controls (42.1% vs 0%, P = 0.039) and associated with tubuloreticular bodies (P = 0.003). Anti-TIF1γ was related with TIF1γ expression in the muscle (P = 0.042).

Conclusion: TIF1α expression in the skin and TIF1γ in the muscle of DM was increased compared to controls. TIF1γ expression in the muscle of IIMs was related to anti-TIF1γ antibody.