ICAP
AC-10 - Punctate nucleolar
Previous Nomenclature nucleolar speckled
Description Densely distributed but distinct grains seen in the nucleoli of interphase cells. In metaphase cells, up to 5 bright pairs of the nucleolar organizer regions (NOR) can be seen within the chromatin body. The cytoplasm of mitotic cells may be slightly positive. e.g. anti-NOR-90, anti-RNA polymerase I
Antigen Association RNA polymerase I, hUBF/NOR-90
Clinical Relevance
First level information
About Clinical Relevance

The AC-10 pattern can be seen in various conditions, including SSc, Raynaud’s phenomenon, SjS, and cancer (52–56)

If the AC-10 pattern is observed in the serum of patients with conditions mentioned above, follow-up testing for anti-NOR90(hUBF) antibodies is to be considered; the antigen is included in disease specific immunoassays (i.e. SSc profile*) (54, 55)

While AC-10 is associated with anti-RNApol I antibodies, these antibodies almost always coexist with anti-RNApol III antibodies which reveal the AC-5 pattern; therefore, if SSc is clinically suspected, it is recommended to perform a follow-up test for anti-RNApol III antibodies (See also AC-5); specific immunoassays for anti-RNApol I antibodies are currently not commercially available (52, 53, 57)

*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
52.
Reimer G, Rose KM, Scheer U, et al. Autoantibody to RNA polymerase I in scleroderma sera. J Clin Invest 1987;79:65–72.
53.
vKuwana M, Kaburaki J, Mimori T, et al. Autoantibody reactive with three classes of RNA polymerases in sera from patients with systemic sclerosis. J Clin Invest 1993;91:1399–404.
54.
Fritzler MJ, von Muhlen CA, Toffoli SM, et al. Autoantibodies to the nucleolar organizer antigen NOR-90 in children with systemic rheumatic diseases. J Rheumatol 1995;22:521–4.
55.
Fujii T, Mimori T, Akizuki M. Detection of autoantibodies to nucleolar transcription factor nor 90/hUBF in sera of patients with rheumatic diseases, by recombinant autoantigen-based assays. Arthritis Rheum 1996;39:1313–8.
56.
Imai H, Ochs RL, Kiyosawa K, et al. Nucleolar antigens and autoantibodies in hepatocellular carcinoma and other malignancies. Am J Pathol 1992;140:859–70.
57.
Yamasaki Y, Honkanen-Scott M, Hernandez L, et al. Nucleolar staining cannot be used as a screening test for the scleroderma marker anti-RNA polymerase I/III antibodies. Arthritis Rheum 2006;54:3051–6.
Second level information
None
Second level information references
None
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Online since 19 May 2015