title: Frequent coexistence of anti-topoisomerase I and anti-U1RNP autoantibodies in African American patients associated with mild skin involvement: a retrospective clinical study.
abstract: BACKGROUND
  The presence of anti-topoisomerase I (topo I) antibodies is a classic scleroderma (SSc) marker presumably associated with a unique clinical subset. Here the clinical association of anti-topo I was reevaluated in unselected patients seen in a rheumatology clinic setting.
  
  
  METHODS
  Sera from the initial visit in a cohort of unselected rheumatology clinic patients (n = 1,966, including 434 systemic lupus erythematosus (SLE), 119 SSc, 85 polymyositis/dermatomyositis (PM/DM)) were screened by radioimmunoprecipitation. Anti-topo I-positive sera were also tested with immunofluorescence and RNA immunoprecipitation.
  
  
  RESULTS
  Twenty-five (15 Caucasian, eight African American, two Latin) anti-topo I positive patients were identified, and all except one met the ACR SSc criteria. Coexistence of other SSc autoantibodies was not observed, except for anti-U1RNP in six cases. When anti-topo I alone versus anti-topo I + U1RNP groups were compared, African American (21% vs. 67%), overlap with SLE (0 vs. 50%; P = 0.009) or PM/DM (0 vs. 33%; P = 0.05) or elevated creatine phosphokinase (CPK) (P = 0.07) were more common in the latter group. In comparison of anti-topo I-positive Caucasians versus African Americans, the latter more frequently had anti-U1RNP (13% vs. 50%), mild/no skin changes (14% vs. 63%; P = 0.03) and overlap with SLE (0 vs. 38%; P = 0.03) and PM/DM (0 vs. 25%; P = 0.05).
  
  
  CONCLUSIONS
  Anti-topo I detected by immunoprecipitation in unselected rheumatology patients is highly specific for SSc. Anti-topo I coexisting with anti-U1RNP in African American patients is associated with a subset of SLE overlapping with SSc and PM/DM but without apparent sclerodermatous changes.
authors.affiliation: Division of Rheumatology and Clinical Immunology, Department of Medicine, University of Florida, 1600 SW Archer Rd, Gainesville, FL, 32610 USA. minoru.satoh@medicine.ufl.edu
authors.forename: Minoru
authors.initials: M
authors.lastname: Satoh
authors.forename: Malgorzata E
authors.initials: ME
authors.lastname: Krzyszczak
authors.forename: Yi
authors.initials: Y
authors.lastname: Li
authors.forename: Angela
authors.initials: A
authors.lastname: Ceribelli
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Ross
authors.forename: Edward K L
authors.initials: EK
authors.lastname: Chan
authors.forename: Mark S
authors.initials: MS
authors.lastname: Segal
authors.forename: Michael R
authors.initials: MR
authors.lastname: Bubb
authors.forename: Eric S
authors.initials: ES
authors.lastname: Sobel
authors.forename: Westley H
authors.initials: WH
authors.lastname: Reeves
mesh_terms: D000328:Adult; D001741:Black or African American / Q000208:ethnology*; D000368:Aged; D001323:Autoantibodies / Q000097:blood / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D004264:DNA Topoisomerases, Type I / Q000276:immunology*; D003882:Dermatomyositis / Q000208:ethnology / Q000276:immunology; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000208:ethnology / Q000276:immunology; D008297:Male; D008875:Middle Aged; D012342:RNA, Small Nuclear / Q000276:immunology*; D012189:Retrospective Studies; D012595:Scleroderma, Systemic / Q000208:ethnology / Q000276:immunology*; D016036:Seroepidemiologic Studies; D012720:Severity of Illness Index; D012871:Skin Diseases / Q000208:ethnology / Q000276:immunology*; D044465:White People / Q000208:ethnology
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D012342:RNA, Small Nuclear; C405483:U1 small nuclear RNA; D004264:DNA Topoisomerases, Type I