AC-8 - Homogeneous Nucleolar
Descrição
Diffuse fluorescence of the entire nucleolus, while the metaphase plate shows no staining. e.g. anti-PM-Scl, anti-Th/To.
Associação Antigênica
PM/Scl-75, PM/Scl-100, Th/To, B23/nucleophosmin, nucleolin, No55/SC65
Doença Associada
SSc, SSc/PM overlap
Relevância Clínica (Primeiro Nível)
Found in patients with SSc, SSc-AIM overlap syndrome, and patients with clinical manifestations of other SARD.
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 (ie, SSc profile).
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.
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.
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.
Relevância Clínica (Segundo Nível)
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.
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.
Referências
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.
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.
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.
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.
Mahler M, Raijmakers R. Novel aspects of autoantibodies to the PM/Scl complex: clinical, genetic and diagnostic insights. Autoimmun Rev 2007;6:432–7.
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.