Additive effect of low-dose etanercept and RB200 in collagen-induced arthritis. Following the onset of arthritis induced by bovine collagen, mice were treated intraperitoneally on the day of disease onset (day 1) and then on days 4 and 7 of disease with RB200 at a dose of 0.5 mg/kg (n = 6) or 10 mg/kg (n = 8) or with a combination of RB200 0.5 mg/kg and etanercept 1 mg/kg (n = 6). Control mice received 5 mg/kg etanercept (n = 6) or 1 mg/kg etanercept (n = 7) or equivalent volumes of PBS (n = 7) intraperitoneally. (a) The increase in clinical score was assessed over a 10-day period, and data are presented as means ± SEM compared to day 1 of arthritis. (b) Paw swelling was measured with callipers, and data are presented as means ± SEM of both hind paws expressed as the difference from baseline (in millimetres). The data were derived from a representative experiment and analysed using two-way analysis of variance vs PBS-treated mice. ns = not significant; **P < 0.01; ***P < 0.001.