Redefining the Scl-70 indirect immunofluorescence pattern: autoantibodies to DNA topoisomerase I yield a specific compound immunofluorescence pattern

Rheumatology (Oxford). 2009 Jun;48(6):632-7. doi: 10.1093/rheumatology/kep070. Epub 2009 Apr 24.


Objectives: To report on a novel IIF pattern specifically associated with antibodies to DNA topo I.

Methods: A novel compound IF pattern, designated Scl-70 pattern, was characterized in routine ANA-HEp-2 IIF screening. Within the last 3 years, all serum samples presenting the Scl-70 pattern at the ANA-HEp2 IIF screening were tested for anti-topo I reactivity. Conversely, 16 serum samples with known anti-topo I reactivity and affinity-purified anti-topo I antibody preparations were tested for the Scl-70 pattern.

Results: The Scl-70 pattern comprised the staining of five cellular regions: nucleus, nucleolus and cytoplasm in interphase cells; nucleolar organizing region (NOR) and chromosomes in mitotic cells. All 81 serum samples selected as Scl-70 pattern reacted with topo I. All 16 anti-topo I samples and antibody preparations reproduced the Scl-70 pattern. This compound IF pattern was consistently observed in different commercial HEp-2 cell slides and in home-made slides with HEp-2 cells and human fibroblasts fixed with alternative protocols. Double IIF experiments demonstrated the co-localization of topo I and human upstream binding factor at the NOR.

Conclusions: The Scl-70 pattern belongs to the group of compound IF patterns that hold strong association with the respective autoantibody specificities, such as that observed with centromere protein F (CENP-F) and nuclear mitotic apparatus-1 (NuMA-1) protein. The identification of the Scl-70 pattern at routine ANA-HEp-2 IIF screening may lead to implementation of specific tests for the identification of anti-topo I antibodies. In addition, the Scl-70 pattern outlines cellular domains other than those previously reported for topo I, which is of interest for further understanding the roles of this enzyme in cell biology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Autoantibodies / immunology*
  • Autoantigens / blood*
  • Cell Line
  • Cell Nucleolus / chemistry
  • Cell Nucleus / chemistry
  • Chromosomes / chemistry
  • Cytoplasm / chemistry
  • DNA Topoisomerases, Type I / immunology*
  • Fluorescent Antibody Technique, Indirect
  • Humans
  • Interphase
  • Mitosis
  • Nuclear Proteins / blood*
  • Nucleolus Organizer Region / chemistry
  • Scleroderma, Systemic / immunology


  • Autoantibodies
  • Autoantigens
  • Nuclear Proteins
  • Scl 70 antigen, human
  • DNA Topoisomerases, Type I