title: Immunodiagnostic significance of anti-RA33 autoantibodies in Saudi patients with rheumatoid arthritis.
abstract: The primary objective of this study was to evaluate and compare the immunodiagnostic significance and utility of anti-RA33 with anti-CCP, RF, and CRP in Saudi patients with rheumatoid arthritis.
  
  
  METHODS
  This was a prospective controlled clinical study conducted at King Abdul Aziz University Tertiary Medical Centre. The sera of 41 RA patients, 31 non-RA patients, and 29 healthy controls were collected. Anti-RA33 and anti-CCP were measured using commercially available ELISA principle kits. RF and CRP were measured using nephelometry.
  
  
  RESULTS
  Anti-RA33 antibodies had the lowest positive and negative predictive values and showed a sensitivity of 7.32% with 95.12% specificity. Of the other three markers (including anti-CCP antibodies, CRP, and RF), only anti-CCP showed specificity of 90.46% with sensitivity of 63.41% compared to non-RA patients + healthy control. There was a significant correlation with rheumatoid factor positivity with anti-CCP. With respect to CRP, a notable correlation was seen only with anti-RA33.
  
  
  CONCLUSIONS
  Compared to rheumatoid factor, anti-CCP antibodies, and C-reactive proteins, the anti-RA33 autoantibodies seem to be not representing as an important additional immunodiagnostic marker in Saudi patients with established RA. RA33 may have more interest in early RA or less severe RA and other systemic connective tissue disorders.
authors.affiliation: Department of Clinical Laboratory Medicine (Diagnostic Immunology Division) and Department of Medical Microbiology and Immunology, Faculty of Medicine, King Abdulaziz University, P.O. Box 80215, Jeddah 21519, Saudi Arabia.
authors.forename: Jamil A
authors.initials: JA
authors.lastname: Al-Mughales
mesh_terms: D000328:Adult; D000974:Antibodies, Antinuclear / Q000097:blood / Q000276:immunology; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood / Q000276:immunology*; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000378:metabolism; D005260:Female; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007159:Immunologic Tests / Q000379:methods; D008297:Male; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000276:immunology*; D012217:Rheumatoid Factor / Q000276:immunology*; D012529:Saudi Arabia
chemical_list: D000974:Antibodies, Antinuclear; D001323:Autoantibodies; D015415:Biomarkers; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D007074:Immunoglobulin G; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide; D002097:C-Reactive Protein; D012217:Rheumatoid Factor