Exam 3 Review:  Chapter 21:  Cell-Mediated Immunity

anergy - A depression or lack of normal immunological function, either generalized or antigen-specific; typically the failure to react to an injected allergen or antigen, e.g., failure to respond to the tuberculin skin test by person with a prior history of TB.

clone - The propagation of genetically identical cells by mitosis and the resulting assemblage of the identical cells; in the immune system, the proliferation of stimulated antigen-specific B and T lymphocytes following exposure to the antigen into functional clones with various defensive functions.

self-recognition - The ability of the immune system to recognize the set of molecules and cells within the individual as "self," i.e., belonging to the body and, therefore, not being foreign; this immune function is centered in the maturation process of B and T lymphocytes in which any anti-self lymphocytes experience negative selection and are either destroyed = deleted or regulated into inactivity.

immunological tolerance - The failure of the immune system to respond to an antigen with any specific responses; it is not simply a failure to recognize an antigen as foreign, but is rather a particular form of active response in which immune defenses are not activated; it includes the "natural" failure to respond to self antigens and the "induced" tolerance to external foreign antigens which may be created by manipulating the immune system, e.g., with repeated allergy injections, or by the application of medications, e.g., the suppression of transplant rejection with corticosteroids and other drugs.

selection - In biological systems, a natural or artificial process which favors or induces survival and perpetuation of one kind of cell or organism over others that die or fail to produce offspring.

positive selection - In the immune system, those situations in which white blood cells are encouraged, i.e., regulated, to differentiate and proliferate; typically, it is the generation of active clones of B and T lymphocytes in response to antigen-presentation and stimulation by various lymphokines during active immune responses (memory lymphocytes clones will also be produced).

negative selection - In the immune system, those situations in which white blood cells are discouraged, i.e., regulated not to differentiate and proliferate; it includes the situation during the maturation process of B and T lymphocytes in which any anti-self lymphocytes are either destroyed = deleted or regulated into inactivity; it also includes the suppressive or negative feedback regulation which decreases the further proliferation and actions of active clones of B and T lymphocytes in response to certain lymphokines during the closing or ending phase of any active immune response when the body is returning to homeostasis.

deletion - In the immune system, those situations in which any anti-self B and T lymphocytes (clones) are destroyed during the maturation process in response to certain lymphokines and other local regulatory substances.

major histocompatibility complex (MHC) antigens - A group of widely distributed cell surface markers (membrane proteins), the histocompatibility antigens*, coded for by the genes of the Major Histocompatability Complex (MHC) (in humans, these genetic blueprints comprise the diverse set of alleles occurring at four loci on the short arm of chromosome 6); these cell surface markers (HLA* antigens) are subdivided into two functional classes, I & II.; these cell surface markers (antigens) permit leukocytes to recognize and distinguish self from non-self tissue cells (Class I) and to recognize and cooperate with other leukocytes and immune defense cells (Class II).  [*Note:  the histocompatibility antigens are also referred to as the human leukocyte antigens or HLA markers.]

MHC Class I antigens = MHC Class I surface markers - A group of widely distributed cell surface markers, the histocompatibility antigens*, coded for by the genes of the Major Histocompatability Complex (MHC) (in humans, these genetic blueprints comprise the diverse set of alleles occurring at four loci on the short arm of chromosome 6); these cell surface markers (antigens) are located on all nucleated body tissue cells; these cell surface markers (antigens) permit leukocytes to recognize and distinguish self from non-self tissue cells.  [*Note:  the histocompatibility antigens are also referred to as the human leukocyte antigens or HLA markers.]

MHC Class II antigens = MHC Class II surface markers  - A group of widely distributed cell surface markers, coded for by the genes of the Major Histocompatability Complex (MHC) (in humans, these genetic blueprints comprise the diverse set of alleles occurring at several loci on the short arm of chromosome 6); these cell surface markers (antigens) are located on a limited number of immune cells, e.g., macrophages and T and B lymphocytes; these cell surface markers (antigens) permit these immune cells, e.g. macrophages and T and B lymphocytes, to recognize and cooperate with each other in antigen-presentation and in the generation of various antigen-specific immune defenses.

immunosurveillance = immunological surveillance - A normal continual monitoring process of the immune system which detects and destroys neoplastic = cancer cells and which tends to break down in immunosuppressed and immunocompromised individuals; it is one of the main functions of the NK = natural killer lymphocytes but also involves some macrophages and T and B lymphocytes.

1.