High diagnostic performance of ELISA detection of antibodies to citrullinated antigens in rheumatoid arthritis.
Suzuki, K 1; Sawada, T 1; Murakami, A 2; Matsui, T 3; Tohma, S 3; Nakazono, K 4; Takemura, M 5; Takasaki, Y 6; Mimori, T 7; Yamamoto, K 1
[Article] Scandinavian Journal of Rheumatology. 32(4):197-204, 2003.

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Objective: We investigated the rheumatoid arthritis (RA) diagnostic performances of anti-cyclic citrullinated peptide antibody (anti-CCP) and antifilaggrin antibody (AFA) in comparison with RF and matrix metalloproteinase-3 (MMP-3).

Methods: We used a second generation enzyme-linked immunosorbent assay (ELISA) kit for the detection of anti-CCP. We constructed recombinant human filaggrin, which was citrullinated in vitro by human peptidylarginine deiminase, and subsequently used it as the coating antigen for AFA-ELISA. A total of 549 RA patients and 208 other rheumatic disease patients were included in the study.

Results: The specificities of anti-CCP (88.9%) and AFA (94.7%) were superior to those of RF (81.7%) and MMP-3 (49.5%). The sensitivity of anti-CCP (87.6%) was superior to all others. However, the sensitivity of AFA (68.7%) was inferior to those of RF (69.8%) and MMP-3 (75.7%). Furthermore, receiver operating characteristic curves of anti-CCP and AFA passed closer to the upper left corner than those of RF and MMP-3, and the areas under the curves (AUC) of AFA and anti-CCP were significantly larger. In addition, the AUC of anti-CCP was significantly larger than that of AFA.

Conclusion: ELISA detection of antibodies to citrullinated antigens, especially a second generation anti-CCP, showed higher discriminative ability than other assays, including RF, and would be useful to aid the diagnosis of RA in clinical practice.

(C) 2003 Scandinavian Rheumatology Research Foundation