RB200 reduces synovial vascularity 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 0.1 mg/kg (n = 6), 1 mg/kg (n = 8) or 10 mg/kg (n = 8). Control mice received an equivalent volume of PBS intraperitoneally (n = 6). Representative CD31-stained sections from the first metatarsal joints of mice are shown. (a) PBS treatment. (b) 0.1 mg/kg RB200. (c) 1 mg/kg RB200. (d) 10 mg/kg RB200. (e) CD31-stained sections were scored subjectively in a blinded fashion. Scale bars are indicated. The criteria assessed included proximity of positive staining to the joint, strength of immunopositive staining and overall status of joint architecture. Statistical analyses were carried out using one-way analysis of variance vs PBS-treated mice. **P < 0.01.