Final answer:
Lymphocytes mediate the adaptive defense system.
Step-by-step explanation:
The mediators of the adaptive defense system, also known as the specific defense system, are lymphocytes.
Lymphocytes are a type of white blood cell that play a crucial role in the adaptive immune response. They can recognize and respond to specific antigens on pathogens.
When an antigen enters the body, lymphocytes, specifically B cells and T cells, bind to the antigen and initiate an immune response. B cells produce antibodies that can bind to and neutralize the pathogen, while T cells can directly destroy infected cells.