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| Previous Nomenclature | None |
| Description | Diffuse fluorescence of the entire nucleolus, while the metaphase plate shows no staining. e.g. anti-PM-Scl, anti-Th/To. |
| Antigen Association | PM/Scl-75, PM/Scl-100, Th/To, B23/nucleophosmin, nucleolin, No55/SC65 |
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Clinical Relevance
First level information About Clinical Relevance & List of Abbreviations |
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▶ Found in patients with SSc, SSc-AIM overlap syndrome, and patients with clinical manifestations of other SARD (44–46) ▶ If limited cutaneous SSc is clinically suspected, it is recommended to perform a follow-up test for anti-Th/To antibodies; the antigen is included in disease specific immunoassays (i.e., SSc profile*) (44, 45) ▶ If SSc-AIM overlap syndrome is clinically suspected, it is recommended to perform a follow-up test for anti-PM/Scl antibody reactivity; the antigen may be included in the routine ENA profile and is included in disease specific immunoassays (i.e., inflammatory myopathy profile* and the SSc profile*); in general, anti-PM/Scl antibodies yield a diffuse nuclear fine speckled staining in addition to the AC-8 pattern (46) ▶ Other antigens recognized include B23/nucleophosmin, No55/SC65, and C23/nucleolin, but the clinical significance of these autoantibodies is not well established; specific immunoassays for these autoantibodies are currently not commercially available Notes: Although some anti-Th/To antibody immunoassays are commercially available, technical issues relating to the limited sensitivity of these immunoassays should be taken in to consideration (44, 47). *Availability of the inflammatory myopathy profile, the SSc profile and the (extended) liver profile may be limited to specialty clinical laboratories. |
| First level information references |
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44. Mahler M, Fritzler MJ, Satoh M. Autoantibodies to the mitochondrial RNA processing (MRP) complex also known as Th/To autoantigen. Autoimmun Rev 2015;14:254-7. 45. Ceribelli A, Cavazzana I, Franceschini F, et al. Anti-Th/To are common antinucleolar autoantibodies in Italian patients with scleroderma. J Rheumatol 2010;37:2071-5. 46. Mahler M, Raijmakers R. Novel aspects of autoantibodies to the PM/Scl complex: clinical, genetic and diagnostic insights. Autoimmun Rev 2007;6:432-7. 47. Mahler M, Gascon C, Patel S, et al. Rpp25 is a major target of autoantibodies to the Th/To complex as measured by a novel chemiluminescent assay. Arthritis Res Ther 2013;15. |
| Second level information |
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▶ The AC‐8 pattern that is the result of the anti‐Th/To reactivity is also seen in patients with SLE, UCTD (i.e., patients with rheumatic symptoms without a SARD diagnosis), SSc sine scleroderma, idiopathic interstitial lung disease or pulmonary hypertension (20, 21) ▶ Patients with autoantibodies revealing the AC‐8 pattern due to anti‐PM/Scl reactivity may have, in addition to the clinical features of AIM and SSc, various clinical manifestations of SLE and SjS (22) |
| Second level information references |
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20. Fischer A, Pfalzgraf FJ, Feghali-Bostwick CA, et al. Anti-Th/To-Positivity in a Cohort of Patients with Idiopathic Pulmonary Fibrosis. J Rheumatol 2006;33:1600-1605. 21. Fischer A, Meehan RT, Feghali-Bostwick CA, et al. Unique characteristics of systemic sclerosis sine scleroderma-associated interstitial lung disease. Chest 2006;130:976-981. 22. Mahler M, Raijmakers R. Novel aspects of autoantibodies to the PM/Scl complex: clinical, genetic and diagnostic insights. Autoimmun Rev 2007;6:432-437. |
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