Anti–signal recognition particle autoantibody in patients with and patients without idiopathic inflammatory myopathy
Article first published online: 9 JAN 2004
Copyright © 2004 by the American College of Rheumatology
Arthritis & Rheumatism
Volume 50, Issue 1, pages 209–215, January 2004
How to Cite
Kao, A. H., Lacomis, D., Lucas, M., Fertig, N. and Oddis, C. V. (2004), Anti–signal recognition particle autoantibody in patients with and patients without idiopathic inflammatory myopathy. Arthritis & Rheumatism, 50: 209–215. doi: 10.1002/art.11484
- Issue published online: 9 JAN 2004
- Article first published online: 9 JAN 2004
- Manuscript Accepted: 25 SEP 2003
- Manuscript Received: 28 APR 2003
To determine the long-term outcome and associated clinical, serologic, and pathologic features in a cohort of patients with connective tissue disease (CTD) and the anti–signal recognition particle (anti-SRP) autoantibody.
Sera and clinical data were collected prospectively from consecutive adult patients with polymyositis (PM; n = 134), dermatomyositis (n = 129), or other CTDs (predominantly systemic sclerosis [SSc; n = 790]). Patients were first evaluated during 1973–2001.
Nineteen patients with the anti-SRP autoantibody were identified, 16 (84%) of whom had pure PM and 3 (2 with SSc and 1 with antisynthetase syndrome) had yet to develop features of myositis after a mean followup of 4.5 years (range 2.5–6 years). More SRP-positive PM patients had severe proximal muscle weakness (50%) and muscle atrophy (67%) at initial presentation compared with antisynthetase-positive PM controls. Cardiac involvement occurred in only 2 of 16 SRP-positive PM patients (13%), and interstitial lung disease was noted in 3 of 13 SRP-positive PM patients (23%) and in the 3 SRP-positive nonmyositis patients. There was a relative lack of inflammation in muscle biopsy specimens from the SRP-positive PM cohort. Other autoantibodies in the SRP-positive patients included Ro/SSA (4 patients), Th/To (1 patient), and anti–PL-12 (1 patient). Survival in the SRP-positive PM patients was comparable with that seen in the cohort of SRP-negative PM patients.
The anti-SRP autoantibody is not specific for PM. Severe muscle weakness and atrophy were prominent features in PM patients with anti-SRP. Cardiac involvement was less common and survival was better in patients with anti-SRP than has previously been reported.