Self-tolerance

In fetal life, if an immature antibody-producing cell shows cell surface anti- body which binds a normal body parts, then the cell dies. Therefore, commonly, in the adult animal no cells exist which can make antibodies against the animal’s own macromolecules.   This incapability to make antibodies against self is called self-tolerance. Moreover, in some disease states the so-called autoimmune diseases the immune system loses its tolerance against self-antigens.