title: Autoantibodies in patients with Down syndrome: early senescence of the immune system or precocious markers for immunological diseases?
abstract: OBJECTIVE
  Down syndrome (DS) patients present several immunological disturbances, with high rates of infections, malignancies and autoimmune phenomena. The present study aims to evaluate the prevalence of autoantibodies in children and adolescents with DS that are not usually investigated, and to establish possible clinical and laboratory associations.
  
  
  METHODS
  One hundred and fifty Caucasoid DS patients from southern Brazil (93M, 57F; median age 4 years) and 105 healthy children (58M, 47F; median age 8 years) were evaluated for the presence of anti-mitochondrial (AMA), smooth-muscle (SMA), liver-kidney microsomal (LKM), nuclear (ANA), gastric parietal cell (GPC) and neutrophil cytoplasmic (ANCA) antibodies, by indirect immunofluorescence, and rheumatoid factor (RF), by turbidimetry.
  
  
  RESULTS
  Forty-three DS patients (28.6%) showed positivity to at least one autoantibody, in comparison with eight of the controls (7.6%; P < 0.001). RF was detected in 28% of the patients and 6.7% of the controls (P < 0.001). ANCA, SMA and ANA were positive in 0.66% of the patients, while AMA, GPC and LKM were negative in all the samples. Currently, none of the RF positive patients has clinical evidence of rheumatic disease.
  
  
  CONCLUSIONS
  Data from the present study suggest that the high incidence of positive RF observed in DS patients might be related to the senescence of the immune system or could be an earlier marker of rheumatic diseases in these patients.
authors.affiliation: Laboratory of Immunopathology, Department of Medical Pathology, Clinical Hospital, Curitiba, Paraná, Brazil.
authors.forename: Shirley Ramos
authors.initials: SR
authors.lastname: da Rosa Utiyama
authors.forename: Renato Mitsunori
authors.initials: RM
authors.lastname: Nisihara
authors.forename: Flávia Raphaela
authors.initials: FR
authors.lastname: Nass
authors.forename: Nanci P
authors.initials: NP
authors.lastname: Oliveira
authors.forename: Patrícia T
authors.initials: PT
authors.lastname: Fiedler
authors.forename: Iara Taborda
authors.initials: IT
authors.lastname: de Messias-Reason
mesh_terms: D000293:Adolescent; D000328:Adult; D019588:Aging, Premature / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood / Q000276:immunology*; D001327:Autoimmune Diseases / Q000097:blood / Q000276:immunology*; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004314:Down Syndrome / Q000097:blood / Q000276:immunology*; D005260:Female; D006801:Humans; D008297:Male; D012217:Rheumatoid Factor / Q000097:blood / Q000276:immunology
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D012217:Rheumatoid Factor