title: Clinical and histopathological features of myopathies in Japanese patients with anti-SRP autoantibodies.
abstract: To elucidate the clinical and histopathological features associated with autoantibodies to the signal recognition particle (SRP), we have studied 23 Japanese patients with this specificity among 3,500 patients with polymyositis/dermatomyositis and other connective tissue diseases. Anti-SRP antibodies were determined based on analysis of RNA and protein components by immunoprecipitation assays. The pathological analysis was performed by using special stainings including alkaline phosphatase, myosin ATPase, and modified Gomori trichrome stainings. Twenty-one (92%) of these 23 patients had myositis, 8 of whom (38%) required cytotoxic agents or intravenous immunoglobulin therapy in addition to corticosteroid therapy. Four patients (16%) had rheumatoid arthritis, two of whom had no features of myositis. Muscle biopsy specimens of 11 patients were examined histologically in detail. All 11 had muscle fiber necrosis and/or regeneration, but only one had infiltration of inflammatory cells. Six of the 11 (55%) patients showed type I fiber predominance by ATPase staining, while eight control myositis patients without anti-SRP antibodies did not. There was no correlation of other neurogenic features in histology with the presence of anti-SRP antibodies. These studies suggest that anti-SRP autoantibodies are most likely to be related to myopathies that are resistant to corticosteroid therapy and without inflammation histopathologically.
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Takada
authors.forename: Michito
authors.initials: M
authors.lastname: Hirakata
authors.forename: Akira
authors.initials: A
authors.lastname: Suwa
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kaneko
authors.forename: Masataka
authors.initials: M
authors.lastname: Kuwana
authors.forename: Tadayuki
authors.initials: T
authors.lastname: Ishihara
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Ikeda
mesh_terms: D000293:Adolescent; D000328:Adult; D044466:Asian People; D001323:Autoantibodies / Q000097:blood* / Q000302:isolation & purification; D003882:Dermatomyositis / Q000175:diagnosis / Q000473:pathology; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D009135:Muscular Diseases / Q000175:diagnosis* / Q000473:pathology; D017285:Polymyositis / Q000175:diagnosis / Q000473:pathology; D018271:Signal Recognition Particle / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D018271:Signal Recognition Particle