ABSTRACT
Activation of peripheral T cells by foreign and self antigens is under stringent control by different mechanisms, both thymic and peripheral (1). Control of T cell reactivity is accomplished by three major types of mechanisms: 1) deletion, the physical elimination of T cells specific for a given antigen, 2) anergy, the functional incapacity of T cells to respond to antigen, and 3) suppression, the inhibition of T cell function by a regulatory (suppressor) cell. The failure of these mechanisms may lead to autoimmune diseases.
