AC-17 - Cytoplasmic fibrillar segmental
Previous Nomenclature None
Description Enhanced decoration of short segments, periodic dense bodies, along the stress fibers. e.g. anti-alpha-actinin, anti-vinculin.
Antigen Association alpha-actinin, vinculin
Clinical Relevance
First level information
About Clinical Relevance & List of Abbreviations

Found very infrequently in a routine serology diagnostic setting

Antigens recognized include α-actinin and vinculin; specific immunoassays for these autoantibodies are currently not commercially available

First level information references
Second level information

Autoantibodies to α-actinin:

In SLE and lupus nephritis cross-reactive anti-α-actinin and anti-dsDNA autoantibodies have been reported as pathogenic (21)

Reported as part of the anti-cell membrane antibody spectrum that characterize patients with lupus nephritis; also reported as a biomarker to differentiate patients with lupus nephritis from those without renal involvement (22, 23)

Reported with relatively high prevalence (~40%) in patients with AIH type 1 and associated with more severe disease, clinical and histological disease activity, predictor of therapeutic response, and double positivity with anti-ssDNA antibodies (24-26)

Autoantibodies to vinculin:

Reported in 2 of 31 patients with chronic inflammatory demyelinating neuropathy (27)


Notes: Most reports describe autoantibodies directly binding to specific antigens (i.e. antigen-specific immunoassays) and none actually shows correlations with the AC-17 pattern as such; specific immunoassays for these autoantibodies are currently not commercially available.

Second level information references
Zhao Z, Weinstein E, Tuzova M, et al. Cross-reactivity of human lupus anti-DNA antibodies with alpha-actinin and nephritogenic potential. Arthritis Rheum 2005;52:522-30.
Seret G, Canas F, Pougnet-Di Costanzo L, et al. Anti-alpha-actinin antibodies are part of the anti-cell membrane antibody spectrum that characterize patients with lupus nephritis. J Autoimmun 2015;61:54-61.
Zhang WH, Pan HF, Zhao XF, et al. Anti-alpha-actinin antibodies in relation to new-onset systemic lupus erythematosus and lupus nephritis. Mol Biol Rep 2010;37:1341-5.
Gueguen P, Dalekos G, Nousbaum JB, et al. Double reactivity against actin and alpha-actinin defines a severe form of autoimmune hepatitis type 1. J Clin Immunol 2006;26:495-505.
Renaudineau Y, Dalekos GN, Gueguen P, et al. Anti-alpha-actinin antibodies cross-react with anti-ssDNA antibodies in active autoimmune hepatitis. Clin Rev Allergy Immunol 2008);34:321-5.
Zachou K, Oikonomou K, Renaudineau Y, et al. Anti-alpha actinin antibodies as new predictors of response to treatment in autoimmune hepatitis type 1. Aliment Pharmacol Ther 2012;35:116-25.
Beppu M, Sawai S, Satoh M, et al. Autoantibodies against vinculin in patients with chronic inflammatory demyelinating polyneuropathy. J Neuroimmunol 2015;287:9-15.
How to deal with just a “nuclear speckled” IFA report?
In my practice I have followed patients with ANA findings, with a nuclear speckled pattern (without specifying whether fine/dense/coarse), in patients with very heterogeneous phenotypes, some with a clinical picture that suggests further investigation of systemic autoimmune disease (one patient with proximal muscle weakness and skin thickening) and others who represent only non-specific findings. In such situations, as a precaution, I request more specific autoantibodies. However, this pattern (nuclear speckled pattern) is not described by the "ICAP" and I am in doubt about which antigenic association it represents, even to guide which autoantibody may be present and which ones to look after. How to interpret this pattern? Does the lab describe it when it is not possible to "refine" such a conclusion? Could this be associated with deficiency in the methodology, sample, interpretation?
Online since 19 May 2015