In vivo E-selectin-targeted fluorescence imaging in collagen-induced arthritis following treatment with low dose etanercept and/or RB200. 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 or 1 mg/kg etanercept or with a combination of 0.5 mg/kg RB200 and 1 mg/kg etanercept. Control mice received equivalent volumes of PBS intraperitoneally. For imaging, mice were injected intravenously with near-infrared dye-labelled anti-E-selectin antibody (5 μg in 200 μl). Images were obtained eight hours after injection of the dye-antibody conjugate. Left panels show representative fluorescent images obtained after application of a colour wheel to depict signal intensity. Right panels show corresponding images coregistered with X-rays after subtraction of background fluorescence.