Anergy is a term in
immunobiology that describes a lack of reaction by the body's defense mechanisms to foreign substances, and consists of a direct induction of peripheral
lymphocyte tolerance. An individual in a state of anergy often indicates that the
immune system is unable to mount a normal immune response against a specific
antigen, usually a self-antigen. Lymphocytes are said to be anergic when they fail to respond to their specific antigen. Anergy is one of three processes that induce tolerance, modifying the immune system to prevent self-destruction (the others being
clonal deletion and
immunoregulation).