Effect of Plumbagin on elicitation of Ig G subclasses specific to collagen type II arthritis. Two groups of DBA/1 mice were immunized with 0.1 ml of bovine type II collagen along with CFA intradermally at the base of the tail. Booster dose was given on day 21. Test group was treated with Plumbagin. 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 IgG subclasses by ELISA. p-value≤0.05 was significant.