Effect of Plumbagin on the production of IFN-γ in collagen Type II induced arthritis mice. Four 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. Normal group did not receive any injection. Test groups were treated intraperitoneally with Plumbagin (3.3 mg/kg), (6.6 mg/kg) and (13.3 mg/kg) respectively. Control group was treated with vehicle alone. At the end of the experiment, mice were sacrificed and Spleenic T lymphocytes isolated from arthritic mice, Plumbagin treated mice and normal mice were incubated with 1μg and 2μg of Con A and maintained the conditions similar to the previous culture experiments. Cultures supernatants were collected and IFN-γ production was estimated by ELISA. p-value≤0.05 was significant.