Background/Objectives: Anti-centromere antibodies are associated with limited cutaneous Systemic Sclerosis (lcSSc) and in general, with a more favorable prognosis for SSc. Centromere pattern (AC-3) observed in the immunofluorescence assay in HEp-2 cells (HEp-2-IFA) suggests the presence of antibodies against CENP antigens, mainly CENP-B/A. In this study, we evaluated the frequency of reactivity to CENP-B and CENP-A in samples with an AC-3 pattern in the HEp-2-IFA. We also correlated the demographic and clinical characteristics of SSc patients according to the presence of the AC-3 pattern. Methods: Samples from 39 SSc patients with AC-3 pattern were included and evaluated for CENP-B/A reactivity by line-blot and indirect ELISA. As controls, 48 lcSSc without the AC-3 pattern (Non-AC-3 group) were included. Clinical characteristics were recovered for 69 patients, 21 with AC-3 and all those in the Non-AC-3 group. Results : Out of 39 samples with AC-3, 33 (84.6%) were reactive against CENP-B and 32 (82.1%) were reactive against CENP-A using the line-blot assay. Using anti-CENP-B ELISA, 36 (92.3%) of the samples with AC-3 were positive for anti-CENP-B. There was 79.5% concordance for CENP-B reactivity between ELISA and line-blot. Using the immunoblot assay, 27 (69.2%) of the samples with AC-3 were reactive against CENP-B and CENP-A, and one sample was positive only for CENP-A. Altogether, 38 samples (97.4%) were reactive against CENP-B by at least one method and all 39 samples (100%) were positive for either CENP-B or CENP-A in at least one of the tests. Regarding the clinical features, interstitial lung disease was less frequent in patients with AC-3 pattern compared to Non-AC-3 (10% versus 54.2%; p=0.001). Other organ involvement parameters had similar frequencies between the groups. Conclusions : In conclusion, the HEp-2-IFA method was 100% sensitive in detecting antibodies to CENP-A and CENP-B. Anti-CENP-B is the predominant autoantibody in samples yielding the AC-3 pattern, but exclusive anti-CENP-A reactivity was observed less frequently. Among lcSSc patients, anti-centromere reactivity was associated with less frequent lung involvement.

The authors have declared no competing interest.

This study was funded by Sao Paulo Government agency FAPESP (Sao Paulo State Research Foundation) grant numbers #2017/20745-1 and #2021/04588-9, granted to G.D.K. and L.D. Additionally, L.E.C.A. was supported by the Brazilian research agency National Council for Research (CNPq), grant # PQ-1D 310334/2019-5.

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Ethics committee of Federal University of Sao Paulo - Brazil gave ethical approval for this work (Plataforma Brasil CAAE: 59126320.1.0000.5505).

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All data produced in the present study are available upon reasonable request to the authors by qualified researchers.