title: Anti-C1q, anti-chromatin/nucleosome, and anti-dsDNA antibodies in juvenile systemic lupus erythematosus patients.
abstract: OBJECTIVE
  To evaluate the presence of anti-C1q, anti-chromatin/nucleosome and anti-double stranded DNA (dsDNA) antibodies in juvenile systemic lupus erythematosus (JSLE) and controls.
  
  
  METHODS
  Sixty-seven JSLE and 34 healthy controls were analyzed for the presence of anti-C1q, anti-chromatin/nucleosome, and anti-dsDNA antibodies by ELISA. C1q levels were evaluated by radial immunodiffusion.
  
  
  RESULTS
  The mean current age was similar in JSLE patients and controls (14.6 ± 3.86 vs. 13.6 ± 2.93 years, P = 0.14). Higher frequencies of anti-C1q, anti-chromatin/nucleosome, and anti-dsDNA antibodies were observed in JSLE compared to controls (20% vs. 0%, P = 0.0037; 48% vs. 0%, P < 0.0001 and 69% vs. 3%, P < 0.0001, respectively). The median of anti-C1q, anti-chromatin/nucleosome, and antidsDNA antibodies were also significantly higher in JSLE patients than in controls [9.6 (5.5-127) vs. 7.5 (5-20) units, P = 0.0006; 18 (1.9-212) vs. 3.2 (1.7-17) units, P < 0.0001; and 111 IU/mL (6-741) vs. 14 (6-33) IU/mL; P < 0.0001, respectively]. The sensitivity for anti-C1q, anti-chromatin/nucleosome, and anti-dsDNA antibodies was 21% (CI: 11-33), 49% (CI: 36-62), and 70% (CI: 57-81). The specificity was 100% (CI: 88-100), 100% (88-100), and 97% (CI: 83-99), respectively. A positive correlation was found between anti-dsDNA levels and both anti-C1q (r = 0.51; CI: 0.29-0.68; P < 0.0001) and anti-chromatin/nucleosome antibodies (r = 0.87; CI: 0.79-0.92; P < 0.0001) levels. A negative correlation was observed between anti-C1q and C1q levels (r = -0.33; CI: -0.56-0.05; P = 0.018). The frequency of anti-dsDNA was higher in patients with SLEDAI-2K >1 (P = 0.0047) and no differences were observed in the frequencies of these three autoantibodies and nephritis (P > 0.05).
  
  
  CONCLUSIONS
  Our study demonstrated an elevated specificity for lupus diagnosis involving the three autoantibodies, especially anti-C1q and anti-chromatin/nucleosome.
authors.affiliation: Unidade de Reumatologia Pediátrica Instituto da Criança, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, Av. Dr. Enéas Carvalho Aguiar 647-Pinheiros, São Paulo, SP, Brazil. adriana.jesus@icr.usp.br
authors.forename: Adriana Almeida de
authors.initials: AA
authors.lastname: Jesus
authors.forename: Lucia Maria Arruda
authors.initials: LM
authors.lastname: Campos
authors.forename: Bernadete Lourdes
authors.initials: BL
authors.lastname: Liphaus
authors.forename: Magda
authors.initials: M
authors.lastname: Carneiro-Sampaio
authors.forename: Cristóvão Luis Pitangueira
authors.initials: CL
authors.lastname: Mangueira
authors.forename: Eliane Aparecida
authors.initials: EA
authors.lastname: Rosseto
authors.forename: Clovis Artur Almeida da
authors.initials: CA
authors.lastname: Silva
authors.forename: Morton
authors.initials: M
authors.lastname: Scheinberg
mesh_terms: D001323:Autoantibodies / Q000097:blood*; D002648:Child; D002843:Chromatin / Q000276:immunology*; D015922:Complement C1q / Q000276:immunology*; D004247:DNA / Q000276:immunology*; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000097:blood* / Q000175:diagnosis* / Q000276:immunology; D008181:Lupus Nephritis / Q000097:blood / Q000276:immunology; D008297:Male; D009707:Nucleosomes / Q000276:immunology*; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity
chemical_list: D001323:Autoantibodies; D002843:Chromatin; D009707:Nucleosomes; D015922:Complement C1q; D004247:DNA