 |
Antibody Diversity - The phenomenon of immense variability characteristic of ANTIBODIES, which enables the IMMUNE SYSTEM to react specifically against the essentially unlimited kinds of ANTIGENS it encounters. Antibody diversity is accounted for by three main theories: (1) the Germ Line Theory, which holds that each antibody-producing cell has genes coding for all possible antibody specificities, but expresses only the one stimulated by antigen; (2) the Somatic Mutation Theory, which holds that antibody-producing cells contain only a few genes, which produce antibody diversity by mutation; and (3) the Gene Rearrangement Theory, which holds that antibody diversity is generated by the rearrangement of VARIABLE REGION gene segments during the differentiation of the ANTIBODY-PRODUCING CELLS. |
|
Antibody Formation - The proliferation and differentiation of B-LYMPHOCYTES into PLASMA CELLS or memory cells. On stimulation by ANTIGENS, those cells then produce ANTIBODIES. |
|
Antibody Specificity - The property of antibodies which enables them to react with some ANTIGENIC DETERMINANTS and not with others. Specificity is dependent on chemical composition, physical forces, and molecular structure at the binding site. |
|
Antigen-Antibody Reactions |
|
Autoimmunity - Process whereby the immune system reacts against the body's own tissues. Autoimmunity may produce or be caused by AUTOIMMUNE DISEASES. |
|
Complement Activation - The sequential activation of serum components C1 through C9, initiated by an erythrocyte-antibody complex or by microbial polysaccharides and properdin, and producing an inflammatory response. |
|
Cross-Priming - Class I-restricted activation of CD8-POSITIVE LYMPHOCYTES resulting from ANTIGEN PRESENTATION of exogenous ANTIGENS (cross-presentation). This is in contrast to normal activation of these lymphocytes (direct-priming) which results from presentation of endogenous antigens. |
|
Cytotoxicity, Immunologic - The phenomenon of target cell destruction by immunologically active effector cells. It may be brought about directly by sensitized T-lymphocytes or by lymphoid or myeloid "killer" cells, or it may be mediated by cytotoxic antibody, cytotoxic factor released by lymphoid cells, or complement. |
|
Dose-Response Relationship, Immunologic - A specific immune response elicited by a specific dose of an immunologically active substance or cell in an organism, tissue, or cell. |
|
Histamine Release - The secretion of histamine from mast cell and basophil granules by exocytosis. This can be initiated by a number of factors, all of which involve binding of IgE, cross-linked by antigen, to the mast cell or basophil's Fc receptors. Once released, histamine binds to a number of different target cell receptors and exerts a wide variety of effects. |
|
HIV Seronegativity - Immune status consisting of non-production of HIV antibodies, as determined by various serological tests. |
|
Immune Tolerance - The specific failure of a normally responsive individual to make an immune response to a known antigen. It results from previous contact with the antigen by an immunologically immature individual (fetus or neonate) or by an adult exposed to extreme high-dose or low-dose antigen, or by exposure to radiation, antimetabolites, antilymphocytic serum, etc. |
|
Immunity, Active - Resistance to a disease agent resulting from the production of specific antibodies by the host, either after exposure to the disease or after vaccination. |
|
Immunity, Cellular - Those manifestations of the immune response which are mediated by antigen-sensitized T-lymphocytes via lymphokines or direct cytotoxicity. This takes place in the absence of circulating antibody or where antibody plays a subordinate role. |
|
Immunity, Herd - The non-susceptibility to infection of a large group of individuals in a population. A variety of factors can be responsible for herd immunity and this gives rise to the different definitions used in the literature. Most commonly, herd immunity refers to the case when, if most of the population is immune, infection of a single individual will not cause an epidemic. Also, in such immunized populations, susceptible individuals are not likely to become infected. Herd immunity can also refer to the case when unprotected individuals fail to contract a disease because the infecting organism has been banished from the population. |
|
Immunity, Maternally-Acquired - Resistance to a disease-causing agent induced by the introduction of maternal immunity into the fetus by transplacental transfer or into the neonate through colostrum and milk. |
|
Immunity, Mucosal - Nonsusceptibility to the pathogenic effects of foreign microorganisms or antigenic substances as a result of antibody secretions of the mucous membranes. Mucosal epithelia in the gastrointestinal, respiratory, and reproductive tracts produce a form of IgA (IMMUNOGLOBULIN A, SECRETORY) that serves to protect these ports of entry into the body. |
|
Immunity, Natural - The capacity of a normal organism to remain unaffected by microorganisms and their toxins. It results from non-specific mechanisms such as naturally occurring antiviral and bactericidal substances, PHAGOCYTOSIS, and constitutional factors such as BODY TEMPERATURE, oxygen tension, and age. |
|
Immunocompetence - The ability of lymphoid cells to mount a humoral or cellular immune response when challenged by antigen. |
|
Immunocompromised Host - A human or animal whose immunologic mechanism is deficient because of an immunodeficiency disorder or other disease or as the result of the administration of immunosuppressive drugs or radiation. |
|
Immunologic Memory - The altered state of immunologic responsiveness resulting from initial contact with antigen, which enables the individual to produce antibodies more rapidly and in greater quantity in response to secondary antigenic stimulus. |
|
Neuroimmunomodulation - Influences of the nervous system (brain, spinal cord, autonomic and peripheral nervous systems) upon the immune system, principally by biochemical (i.e., neurotransmitters, receptors, etc.) and by direct neural routes. This is a two-way information transfer system. |
|
Neutrophil Activation - The process in which the neutrophil is stimulated by diverse substances, resulting in degranulation and/or generation of reactive oxygen products, and culminating in the destruction of invading pathogens. The stimulatory substances, including opsonized particles, immune complexes, and chemotactic factors, bind to specific cell-surface receptors on the neutrophil. |
|
Neutrophil Infiltration - The diffusion or accumulation of neutrophils in tissues or cells in response to a wide variety of substances released at the sites of inflammatory reactions. |
|
T-Cell Antigen Receptor Specificity - The property of the T-CELL RECEPTOR which enables it to react with some antigens and not others. The specificity is derived from the structure of the receptor's variable region which has the ability to recognize certain antigens in conjunction with the MHC (MAJOR HISTOCOMPATABILITY COMPLEX) molecule. |
|
Tumor Escape - The ability of tumors to evade destruction by the IMMUNE SYSTEM. Theories concerning possible mechanisms by which this takes place involve both cellular immunity (IMMUNITY, CELLULAR) and humoral immunity (ANTIBODY FORMATION), and also costimulatory pathways related to CD28 antigens (ANTIGENS, CD28) and CD80 antigens (ANTIGENS, CD80). |
MedicalGlossary.org is designed as a free, browsable resource for all. The medical terms and definitions are not intended to replace medical informaion provided by licensed healthcare professionals. Please see a doctor if you need medical assistance. Don't see the medical term you were researching? Send us an e-mail from our "about us" page. We will do our best to research and classify new medical terms in a timely manner. Our current list of medical terms is over 26,000. Data sources include the U.S. National Library of Medicine, 2004 Medical Subject Headings.
