title: Measurement and evaluation of isotypes of anti-citrullinated fibrinogen and anti-citrullinated alpha-enolase antibodies in juvenile idiopathic arthritis.
abstract: OBJECTIVE
  Our objective was to evaluate sera from juvenile idiopathic arthritis (JIA) patients to investigate the presence of isotypes (IgA, IgG, IgM) of anti-citrullinated fibrinogen and anti-α-enolase antibodies and their association with rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibody isotypes.
  
  
  METHODS
  Sera were obtained from 89 JIA patients and were measured for isotypes (IgA, IgM) of anti-citrullinated and native fibrinogen and anti-α-enolase antibodies by enzyme-linked immunosorbent assay. Results were compared to anti-CCP antibody isotypes and RF isotypes, in addition to previously measured IgG anti-citrullinated fibrinogen and α-enolase antibodies.
  
  
  RESULTS
  IgA anti-citrullinated fibrinogen antibodies were positive in 20 JIA patients and IgM in 11 JIA patients. Two IgM RF-positive polyarthritis patients were positive for all 3 isotypes of anti-citrullinated fibrinogen antibodies. IgA anti-citrullinated α-enolase antibodies were positive in 7 JIA patients and IgM in 9 JIA patients. IgA and IgG anti-citrullinated fibrinogen antibodies were commonly found in JIA patients positive for IgG anti-CCP antibodies and IgM RF. IgG anti-CCP antibodies and IgM RF levels were significantly higher in JIA patients with 3 or more anti-citrullinated autoantibody isotypes present.
  
  
  CONCLUSIONS
  We have shown that isotypes of anti-citrullinated fibrinogen and α-enolase can be found in the serum of children with JIA of all onset types. Citrullinated autoantibody isotype diversity may indicate a more severe disease course in JIA patients.
authors: Division of Adult and Pediatric Rheumatology, Saint Louis University Medical Center, Saint Louis, USA. mooretl@slu.edu.
authors: Terry L
authors: TL
authors: Moore
authors: Brooke E
authors: BE
authors: Gillian
authors: Sandra
authors: S
authors: Crespo-Pagnussat
authors: Lance
authors: L
authors: Feller
authors: Anil K
authors: AK
authors: Chauhan
mesh_terms: D000293:Adolescent; D001171:Arthritis, Juvenile / Q000097:blood / Q000175:diagnosis / Q000201:enzymology / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D014408:Biomarkers, Tumor / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D002956:Citrulline / Q000276:immunology*; D004268:DNA-Binding Proteins / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005340:Fibrinogen / Q000276:immunology*; D006801:Humans; D008297:Male; D010456:Peptides, Cyclic / Q000276:immunology; D010751:Phosphopyruvate Hydratase / Q000276:immunology*; D011237:Predictive Value of Tests; D012217:Rheumatoid Factor / Q000097:blood; D012720:Severity of Illness Index; D025521:Tumor Suppressor Proteins / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D014408:Biomarkers, Tumor; D004268:DNA-Binding Proteins; D010456:Peptides, Cyclic; D025521:Tumor Suppressor Proteins; C487763:cyclic citrullinated peptide; D002956:Citrulline; D005340:Fibrinogen; D012217:Rheumatoid Factor; C095157:ENO1 protein, human; D010751:Phosphopyruvate Hydratase