The lack of an immune response to a foreign compound entering the body is called what?

The lack of an immune response to a foreign compound entering the body is called "tolerance." This phenomenon can occur naturally, as in the case of self-tolerance, where the immune system does not attack the body's own tissues. It can also be induced artificially, such as in the context of organ transplants or certain therapies, where the goal is to prevent an immune response against a foreign substance.