[Inhibitory effects of portal venous injection of type II collagen in collagen-induced arthritis]

Collagen-induced arthritis (CIA) is useful animal model for human rheumatoid arthritis. We investigated the inhibitory effects of portal venous (p.v.) injection of type II collagen (CII) in CIA. The arthritis was suppressed by p.v. injection of CII before immunization for CIA induction. The p.v. route was more effective than intravenous or intragastric routes in the induction of tolerance in CIA. The dose of CII necessary for CIA suppression was 10 micrograms/20 g body weight in p.v. injection. Both anti-CII IgG and anti-CII IgG 2 a levels in serum were reduced in mice injected CII before induction of CIA. However, anti-CII IgG 1 levels did not differ between mice injected with CII and mice injected with buffer alone. Thus, the specific reduction in anti-CII IgG 2 a levels in mice treated by p.v. injection before immunization suggests that the suppression of CIA could be responsible for hypofunction of Th 1 cells. Reduction of anti-CII IgG and suppression of arthritis were observed when CII was injected through portal vein after immunization for CIA as well.