Additive effects of low-dose etanercept and RB200 on E-selectin-targeted in vivo fluorescent imaging 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), 1 mg/kg etanercept (n = 7) or equivalent volumes of PBS (n = 7) intraperitoneally. For imaging, mice were injected intravenously with near-infrared dye-labelled anti-E-selectin antibody (5 μg in 200 μl). Images were obtained 2, 8 and 24 hours after injection of the dye-antibody conjugate. (a) The results are expressed in arbitrary units (au) of mean fluorescence intensity (MFI) ± SEM for both paws and were analysed using two-way analysis of variance (ANOVA) vs PBS-treated mice. ns = not significant; ***P < 0.001. For clarity, data derived from animals treated with 10 mg/kg RB200 or 5 mg/kg etanercept were omitted. (b) Data from a representative experiment are presented and expressed in arbitrary units (au) of mean fluorescence intensity (MFI) ± SEM for individual paws eight hours after injection of the dye-antibody conjugate. They were analysed using one-way ANOVA vs PBS-treated mice. ns = not significant; *P < 0.05; **P < 0.01; ***P < 0.001.