Background/Purpose: Anti-human upstream-binding factor (hUBF) antibodies (Abs) have been reported predominantly in patients with connective tissue diseases (CTDs) but have also been reported in non-CTDs such as hepatocellular carcinoma. Because of the low frequency of expression and few case reports on this Abs, there is no consensus on the clinical significance of this Abs. Thus, we aimed to examine the clinical features of patients with anti-hUBF Abs.

Methods: Serum samples were collected from 1042 patients clinically suspected of CTDs. The presence of anti-hUBF Ab was screened by Immunoprecipitation (IP) assays. AutoAbs associated with various CTDs were identified by specific indirect immunofluorescence staining, enzyme-linked immunosorbent assay, or IP assay. Clinical characteristics of systemic sclerosis (SSc) patients were first analyzed among patients positive for anti-hUBF Abs or negative for this Abs. We next compared the clinical features among three subgroups: Anti-hUBF Abs, anti-centromere Abs (ACA), and anti-topoisomerase I (topo I) Abs. Statistical analyses were performed at a 0.05 significance level using SPSS version 27 (IBM, Tokyo, Japan).

Results: Of 1042 patients, 19 (1.82%) were positive for anti-hUBF Abs. Of the 19 patients, 10 were diagnosed with undifferentiated connective tissue disease (UCTD), 6 were SSc, and 3 were others. Of the 10 patients with UCTD, 5 were referred to our hospital suspected of SSc. All 5 patients did not fulfill the 2013 American College of Rheumatology/European League Against Rheumatism classification criteria, but 3 of them got 7 points which was a relatively high score. Of the 6 patients with SSc, anti-hUBF-positive patients had a significantly lower modified Rodnan total skin thickness score (mRSS) than those with anti-hUBF-negative patients (2[0-2] vs 7[0-49], p< 0.01). Compared with anti-topo I Abs, anti-hUBF-positive patients had a significantly lower mRSS (2[0-2] vs 13[0-42], p< 0.01) and lower incidence of scleroderma renal crisis (0/6 vs 8/184, p< 0.01). Whereas compared with ACA, anti-hUBF-positive patients had a higher incidence of interstitial lung disease (ILD) but there was no significant difference (4/6 vs 19/239).

Conclusion: Anti-hUBF Abs were positive predominantly in CTDs and UCTD. In CTDs, SSc had a high ratio and they seemed to have lower mRSS and higher incidence of ILD. In UCTD, they should be followed up carefully because they might be CTDs in the future.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-features-of-anti-hubf-antibodies-positive-patients-a-single-center-retrospective-study/