Anti-cyclic citrullinated peptide antibodies and rheumatoid factor in rheumatoid arthritis patients and relatives from Brazil.

OBJECTIVES 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. CONCLUSION 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.