title: Anti-cyclic citrullinated peptide antibodies and rheumatoid factor in rheumatoid arthritis patients and relatives from Brazil.
abstract: OBJECTIVE
  To evaluate the prevalence of anti-cyclic citrullinated peptide (anti-CCP) antibodies and RF in RA patients and their relatives from Southern Brazil.
  
  
  METHODS
  Anti-CCP2 and IgM-RF were evaluated in 156 RA patients and 200 relatives. Sera from 100 healthy unrelated individuals were used as control. The anti-CCP2 was detected by ELISA and the IgM-RF using the latex agglutination test.
  
  
  RESULTS
  We identified 117 anti-CCP2 (75%)-positive and 106 RF (67.9%)-positive patients. Anti-CCP2 was increased in relatives (5.5%; 11/200) when compared with unrelated individuals (1%; P = 0.050). Titre of anti-CCP2 in RA patients did not differ from relatives [140.4 (75.7) vs 115.6 (84.2) U, respectively; P = 0.30]. Positive relatives were younger than patients for anti-CCP2 (P = 0.0081), RF (P < 0.001) and both concomitantly (P = 0.012), and although there was no difference for anti-CCP2 positivity according to gender, increased RF positivity and concomitant anti-CCP2/RF were observed in the female relatives (P = 0.067 and 0.082, respectively). No difference regarding the relative degree of tobacco use in relatives was detected. Among the 11 anti-CCP2-positive relatives, 2 females had RA diagnosis established and 6 individuals presented with joint symptoms suggestive of RA.
  
  
  CONCLUSIONS
  The results demonstrate a significant positivity of anti-CCP2 in relatives of RA patients from Brazil and reinforce the importance of serological tools to identify undiagnosed RA.
authors.affiliation: Laboratory of Immunopathology, Clinical Hospital, Federal University of Paraná, Curitiba, Paraná, Brazil.
authors.forename: Isabela
authors.initials: I
authors.lastname: Goeldner
authors.forename: Thelma L
authors.initials: TL
authors.lastname: Skare
authors.forename: Iara T
authors.initials: IT
authors.lastname: de Messias Reason
authors.forename: Renato M
authors.initials: RM
authors.lastname: Nisihara
authors.forename: Marília B
authors.initials: MB
authors.lastname: Silva
authors.forename: Shirley R da Rosa
authors.initials: SR
authors.lastname: Utiyama
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000974:Antibodies, Antinuclear / Q000235:genetics*; D001172:Arthritis, Rheumatoid / Q000235:genetics* / Q000503:physiopathology; D001938:Brazil; D016022:Case-Control Studies; D002648:Child; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D010456:Peptides, Cyclic / Q000037:antagonists & inhibitors* / Q000235:genetics; D011237:Predictive Value of Tests; D012217:Rheumatoid Factor / Q000235:genetics*; D013223:Statistics as Topic; D055815:Young Adult
chemical_list: D000974:Antibodies, Antinuclear; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide; D012217:Rheumatoid Factor