Effect of 6-month treatment with tumour necrosis factor (TNF) antagonists on anti-citrullinated glucose-6-phosphate isomerase peptide-2 (CCG-2 (a), CCG-4 (b), CCG-7 (c) and anti-cyclic citrullinated α-enolase peptide (CEP)-1 (d) antibodies. The treatment decreased anti-CCG-2 antibodies (n = 23) [optical density (OD) 1·237–0·906, P < 0·001, paired t-test] and anti-CCG-7 antibodies (n = 26) (OD 0·785–0·623, P < 0·05, paired t-test). The same treatment had no effect on anti-CCG-4 antibodies (n = 30) and anti-CEP-1 antibodies (n = 29). Data represent the optical density values measured at 405 nm (OD 405). Each data line represents an individual subject. Dots and vertical lines represent the mean ± standard deviation values. *P < 0·05; **P < 0·001. (e) Correlation of the changing of anti-CCG-7 antibodies versus disease activity score (DAS)-28 C-reactive protein (CRP). The decreased levels of anti-CCG-7 antibodies (delta OD 405) correlated with the decrease level of DAS28-CRP (delta DAS28-CRP) (r = 0·500, P < 0·05). Each data point represents an individual subject. Solid line indicates the correlation.