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

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Dellavance, Alessandra [UNIFESP]
Gallindo, Cristiane
Soares, Mariana Guanaes [UNIFESP]
Silva, Neusa Pereira da [UNIFESP]
Mortara, Renato Arruda [UNIFESP]
Coelho Andrade, Luis Eduardo [UNIFESP]
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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.
Rheumatology. Oxford: Oxford Univ Press, v. 48, n. 6, p. 632-637, 2009.