Anergy

Article By:

Mueller, Daniel L. Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota.

Last reviewed:October 2019

DOI:https://doi.org/10.1036/1097-8542.033880

The condition of exhibiting no immune response to an antigen. Anergy is a self-tolerance mechanism in which the immune system shows unresponsiveness following an encounter with receptor-recognized antigens. Typically, lymphocytes (the B and T cells of the immune system) act to identify and eliminate foreign antigens (for example, bacteria, toxic substances, and cancer cells) that endanger the individual. The recognition of these variable threats relies on the random production and expression of a unique antigen-binding site on almost every lymphocyte. Lymphocytes whose receptors recognize a foreign antigenic substance are subsequently stimulated by that antigen to multiply. These special lymphocytes play a role in the elimination of the antigen or the cells carrying it. Lymphocytes with a surface antigen receptor that specifically recognizes one of an individual's own self-antigens also can be generated, thus creating the potential for autoimmunity (reaction against one's own cells). Nevertheless, the clinical appearance of autoimmune disease is relatively rare because most individuals possess effective self-tolerance mechanisms to control such autoreactive cells. One major mechanism is clonal deletion: lymphocytes are killed if they recognize a self-antigen during their maturation in the thymus gland (for T cells) or bone marrow (for B cells). However, not all human self-antigens are expressed in these central lymphoid organs while the lymphocytes are developing. Thus, tolerance to an individual's own antigens must also depend on other means, including the self-tolerance mechanism of clonal anergy. Theoretically, autoreactive lymphocytes lose their capacity to multiply following their recognition of a self-antigen in the peripheral immune system. See also: Acquired immunological tolerance; Antigen; Autoimmunity; Cellular immunology; Immunology; Immunosuppression

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