Redefining the Scl-70 indirect immunofluorescence pattern: autoantibodies to DNA topoisomerase I yield a specific compound immunofluorescence pattern.
OBJECTIVE
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.
Dellavance
Alessandra
A
Fleury Medicine and Health, Universidade Federal de São Paulo, São Paulo, Brazil.
Gallindo
Cristiane
C
Soares
Mariana Guanaes
MG
da Silva
Neusa Pereira
NP
Mortara
Renato Arruda
RA
Andrade
Luís Eduardo Coelho
LE
D001323:Autoantibodies / Q000276:immunology*; D001324:Autoantigens / Q000097:blood*; D002460:Cell Line; D002466:Cell Nucleolus / Q000737:chemistry; D002467:Cell Nucleus / Q000737:chemistry; D002875:Chromosomes / Q000737:chemistry; D003593:Cytoplasm / Q000737:chemistry; D004264:DNA Topoisomerases, Type I / Q000276:immunology*; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007399:Interphase; D008938:Mitosis; D009687:Nuclear Proteins / Q000097:blood*; D009697:Nucleolus Organizer Region / Q000737:chemistry; D012595:Scleroderma, Systemic / Q000276:immunology
D001323:Autoantibodies; D001324:Autoantigens; D009687:Nuclear Proteins; C048100:Scl 70 antigen, human; D004264:DNA Topoisomerases, Type I