(immunosuppressive) An agent that decreases the body's immune responses. It reduces the body's ability to fight infections and other diseases, such as cancer. Immunosuppressants may be used to keep a person from rejecting a bone marrow or organ transplant. They are also used in the treatment of conditions marked by over-active immune responses, such as auto-immune diseases and allergies.

Agents that suppress immune function by one of several mechanisms of action. Classical cytotoxic immunosuppressants act by inhibiting DNA synthesis. Others may act through activation of T-CELLS or by inhibiting the activation of HELPER CELLS. While immunosuppression has been brought about in the past primarily to prevent rejection of transplanted organs, new applications involving mediation of the effects of INTERLEUKINS and other CYTOKINES are emerging.

Immunosuppressant, any agent in a class of drugs that is capable of inhibiting the immune system. Immunosuppressants are used primarily to prevent the rejection of an organ following transplantation and in the treatment of autoimmune disease. Among the agents that are most effective for transplant...