title: Anti-carbamylated protein antibodies in unaffected first-degree relatives of rheumatoid arthritis patients: lack of correlation with anti-cyclic citrullinated protein antibodies and rheumatoid factor.
abstract: OBJECTIVE
  To investigate the prevalence of anti-carbamylated protein antibodies (anti-CarP) in the healthy first-degree relatives (HFDRs) of patients with rheumatoid arthritis (RA).
  
  
  METHODS
  We enrolled 141 HFDRs of 63 patients with RA diagnosed accordingly to the 2010 ACR/EULAR criteria. Fifty-six normal healthy subjects (NHS), sex- and age-matched, served as controls. Anti-CarP IgG, anti-cyclic citrullinated peptide antibody (anti-CCP) IgG and rheumatoid factors (RF) isotypes (IgG, IgA, IgM) were assessed by solid-phase ELISA.
  
  
  RESULTS
  Anti-CarP were detectable in 13 HFDRs (9.2%), anti-CCP in 9 (6.3%), IgG-RF in 10 (7%), IgA-RF in 17 (12%), and IgM-RF in 13 (9.2%) HFDRs. Twenty-nine (46%) RA patients were positive for anti-CarP, 31 (49.2%) for anti-CCP, and 34 (53.9%) for RF. One NHS (1.7%) resulted positive for anti-CarP, none for anti-CCP and RF. Anti-CarP showed significantly higher serum levels in RA and HFDRs than in NHS (p<0.0001 and p=0.0012, respectively). A significant correlation between anti-CCP and RF were found among RA patients (p=0.0002), whereas no correlations were reported between autoantibodies tested in the HFDRs.
  
  
  CONCLUSIONS
  Anti-CarP can be found in the sera of HFDRs of RA patients and their prevalence is significantly higher than in NHS. No correlation of anti-CarP with anti-CCP and RF antibodies in RA HFDRs was found.
authors.affiliation: Dipartimento di Medicina Interna e Specialità Mediche, Sapienza Università di Roma, Italy. cristiano.alessandri@uniroma1.it.
authors.forename: C
authors.initials: C
authors.lastname: Alessandri
authors.affiliation: Dipartimento di Medicina Interna e Specialità Mediche, Sapienza Università di Roma, Italy.
authors.forename: I
authors.initials: I
authors.lastname: Bartosiewicz
authors.affiliation: Dipartimento di Medicina Interna e Specialità Mediche, Sapienza Università di Roma, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Pendolino
authors.affiliation: Dipartimento di Medicina Interna e Specialità Mediche, Sapienza Università di Roma, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Mancini
authors.affiliation: Dipartimento di Medicina Interna e Specialità Mediche, Sapienza Università di Roma, Italy.
authors.forename: T
authors.initials: T
authors.lastname: Colasanti
authors.affiliation: Dipartimento di Medicina Interna e Specialità Mediche, Sapienza Università di Roma, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Pecani
authors.affiliation: Dipartimento di Medicina Interna e Specialità Mediche, Sapienza Università di Roma, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Morello
authors.affiliation: Dipartimento di Medicina Interna e Specialità Mediche, Sapienza Università di Roma, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Mastrangelo
authors.affiliation: Dipartimento di Medicina Interna e Specialità Mediche, Sapienza Università di Roma, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Sabatinelli
authors.affiliation: Dipartimento di Medicina Interna e Specialità Mediche, Sapienza Università di Roma, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Riccieri
authors.affiliation: Dipartimento di Medicina Interna e Specialità Mediche, Sapienza Università di Roma, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Di Franco
authors.affiliation: Dipartimento di Medicina Interna e Specialità Mediche, Sapienza Università di Roma, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Ceccarelli
authors.affiliation: Dipartimento di Medicina Interna e Specialità Mediche, Sapienza Università di Roma, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Perricone
authors.affiliation: Dipartimento di Medicina Interna e Specialità Mediche, Sapienza Università di Roma, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Conti
authors.affiliation: Dipartimento di Medicina Interna e Specialità Mediche, Sapienza Università di Roma, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Valesini
mesh_terms: D000328:Adult; D001172:Arthritis, Rheumatoid / Q000175:diagnosis / Q000276:immunology; D001323:Autoantibodies / Q000097:blood*; D001324:Autoantigens / Q000276:immunology; D002219:Carbamates / Q000276:immunology*; D005190:Family; D005192:Family Health; D005260:Female; D006801:Humans; D007159:Immunologic Tests / Q000379:methods; D008297:Male; D010456:Peptides, Cyclic / Q000276:immunology*; D012217:Rheumatoid Factor / Q000097:blood*; D013223:Statistics as Topic
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D002219:Carbamates; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide; D012217:Rheumatoid Factor