Immunosuppression involves an act that reduces the activation or efficacy of the immune system. Some portions of the immune system itself have immuno-suppressive effects on other parts of the immune system, and immunosuppression may occur as an adverse reaction to treatment of other conditions.
An immunosuppressant is any substance that performs immunosuppression of the immunedescribe the image system. They may be either exogenous, as immunosuppressive drugs, or endogenous, as, e. g., testosterone. When the immune system function is suppressed, there is an increased susceptibility to infectious diseases and cancers.