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| Previous Nomenclature | actin-like |
| Description | This pattern is characterized by fibers spanning the long axis of the cells. These cytoskeletal fibers are sometimes decorated with small, discontinuous granular deposits. |
| Antigen Association | actin, non-muscle myosin |
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Clinical Relevance
First level information About Clinical Relevance & List of Abbreviations |
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Autoantibodies to actin: ▶ Found in patients with autoimmune hepatitis (AIH) type 1, chronic hepatitis C virus (HCV) infection, and celiac disease (CD); rare in systemic autoimmune rheumatic diseases. ▶ If AIH type 1 is clinically suspected, it is recommended to confirm reactivity with smooth muscle antibodies (IgG isotype), typically detected by IFA on rodent tissue (liver, stomach, kidney); anti-smooth muscle antibodies are included in the international criteria for AIH type 1 [1]. F-actin is the main target antigen of anti-smooth muscle antibodies in AIH type 1. ▶ Autoantibodies to F-actin are more clinically important than antibodies to G-actin [2-4]. ▶ If CD is clinically suspected, positive IgA anti-actin is correlated with an aggressive form involving severe intestinal mucosa damage [5-7]. Notes: Although anti-F-actin immunoassays are commercially available, technical issues relating to the sensitivity of these immunoassays should be taken into consideration. |
| First level information references |
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| Second level information |
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Autoantibodies to actin: ▶ High prevalence of IgA and/or IgG type anti-actin antibodies have been reported in celiac disease [8, 9] and primary sclerosing cholangitis [10]. Autoantibodies to non-muscle myosin: ▶ Autoantibodies to non-muscle myosin have been described in 3 patients with HCV-positive chronic hepatitis/liver cirrhosis [11]. ▶ Monoclonal antibodies to non-muscle myosin have been reported in chronic lymphocytic leukemia [12]. Note: Specific immunoassays for non-muscle myosin are currently not commercially available. |
| Second level information references |
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1. Liberal R, Grant CR, Longhi MS, Mieli-Vergani G, Vergani D. Diagnostic criteria of autoimmune hepatitis. Autoimmun Rev. 2014;13:435-40. 2. Lidman K, Biberfeld G, Fagraeus A, Norberg R, Torstensson R, Utter G, Carlsson L, Luca J, et al. Anti-actin specificity of human smooth muscle antibodies in chronic active hepatitis. Clin Exp Immunol. 1976;24:266-72. 3. Fusconi M, Cassani F, Zauli D, Lenzi M, Ballardini G, Volta U, Bianchi FB. Anti-actin antibodies: a new test for an old problem. J Immunol Methods. 1990;130:1-8. 4. Chretien-Leprince P, Ballot E, Andre C, Olsson NO, Fabien N, Escande A, Oksman F, Dubuquoi S, et al. Diagnostic value of anti-F-actin antibodies in a French multicenter study. Ann N Y Acad Sci. 2005;1050:266-73. 5. Carroccio A, Brusca I, Iacono G, Di Prima L, Teresi S, Pirrone G, Florena AM, La Chiusa SM, et al. Anti-actin antibodies in celiac disease: correlation with intestinal mucosa damage and comparison of ELISA with the immunofluorescence assay. Clin Chem. 2005;51:917-20. 6. Schirru E, Danjou F, Cicotto L, Rossino R, Macis MD, Lampis R, Jores RD, Congia M. Anti-actin IgA antibodies identify celiac disease patients with a Marsh 3 intestinal damage among subjects with moderate anti-TG2 levels. Biomed Res Int. 2013;2013:630463. 7. Bazzigaluppi E, Parma B, Tronconi GM, Corsin P, Albarello L, Mora S, Barera G. IgA anti-actin antibodies in children with celiac disease: comparison of immunofluorescence with Elisa assay in predicting severe intestinal damage. Ital J Pediatr. 2010;36:25. 8. Pedreira S, Sugai E, Moreno ML, Vazquez H, Niveloni S, Smecuol E, Mazure R, Kogan Z, et al. Significance of smooth muscle/anti-actin autoantibodies in celiac disease. Acta Gastroenterol Latinoam. 2005;35:83-93. 9. Clemente MG, Musu MP, Frau F, Brusco G, Sole G, Corazza GR, De Virgiliis S. Immune reaction against the cytoskeleton in coeliac disease. Gut. 2000;47:520-6. 10. Wunsch E, Milkiewicz M, Norman GL, Laba A, Kruk B, Milkiewicz P. Prognostic significance of anti-gliadin and anti-F-actin immunoglobulin A antibodies in primary sclerosing cholangitis. Pol Arch Intern Med. 2025;135. 11. von Muhlen CA, Chan EKL, Peebles CL, Imai H, Kiyosawa K, Tan EM. Non-muscle myosin as target antigen for human autoantibodies in patients with hepatitis C virus-associated chronic liver diseases. Clin Exp Immunol. 1995;100:67-74. 12. Chu CC, Catera R, Hatzi K, Yan XJ, Zhang L, Wang XB, Fales HM, Allen SL, et al. Chronic lymphocytic leukemia antibodies with a common stereotypic rearrangement recognize nonmuscle myosin heavy chain IIA. Blood. 2008;112:5122-9. |
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