Dose effect of Plumbagin on collagen Type II induced arthritis. Five groups of DBA/1 mice were immunized with 0.1 ml of bovine type II collagen intradermally at the base of the tail. Booster dose was given 3 weeks after primary immunization. Test groups were treated with Plumbagin (3.3 mg/kg), (6.6 mg/kg) and (13.3 mg/kg) and Indomethacin (3 mg/kg) respectively. Control mice were treated with olive oil alone. Retroorbital sera were collected at 3, 5, 7 week intervals after primary immunization for the estimation of anti-type-II collagen antibody (IgG) by ELISA. p-value≤0.05 was significant.