Redox factor-1 in muscle biopsies of patients with inclusion-body myositis

To determine whether redox factor-1 (Ref-1) participates in the pathogenesi s of inclusion-body myositis (IBM), we immunolocalized Ref-1 in muscle biop sies of IBM patients by light- and electron-microscopy. Approximately 70-80 % of the IBM vacuolated muscle fibers had focal inclusions strongly immunor eactive for Ref-1. By immunoelectronmicroscopy, Ref-1 was localized to pair ed-helical filaments, 6-10 nm amyloid-like fibrils and amorphous material. Virtually all regenerating and necrotic muscle fibers in various muscle bio psies had diffusely strong Ref-1 immunoreactivity. At all neuromuscular jun ctions, postsynaptically there was strong Ref-1 immunoreactivity. Our study suggests that Ref-1 plays a role in IBM pathogenesis, and in other patholo gic and normal processes of human muscle. (C) 2000 Published by Elsevier Sc ience Ireland Ltd.