The present invention provides compositions and control method for controlling the activity of regulatory T cells. CD4 ⁺ CD25 ⁺ compositions and the composition of regulatory T cells comprising an expression vector encoding an antigen or antigens recognized relates to a method of controlling the immune response by administering to a mammal a mammal, autoimmune prevention and treatment of diseases and allergic diseases, and provides a useful means for suppressing rejection and graft-versus-host reactions in transplantation. Further immunosuppressed state is released by combined administration of the administration of interferon gamma, or interleukin 12 and interleukin 18. In other words, by combining the sensitization by the action and SEREX antigen such cytokines appropriately, regulatory T cells artificially can operate, autoimmune diseases, reactions associated with organ transplantation, allergic reactions and tumor immunity it can be applied to a control.