Campbell Biology Ap Ch 43 Terms

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ABO blood groups

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Genetically determined classes of human blood that are based on the presence or absence of carbohydrates A and B on the surface of red blood cells. The ABO blood group phenotypes, also called blood types, are A, B, AB, and O.

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active immunity

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Immunity conferred by recovering from an infectious disease.

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agglutination

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An antibody-mediated immune response in which bacteria or viruses are clumped together, effectively neutralized, and opsonized.

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AIDS (acquired immunodeficiency syndrome)

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The name of the late stages of HIV infection; defined by a specified reduction of T cells and the appearance of characteristic secondary infections.

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anaphylactic shock

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An acute, life-threatening, allergic response.

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antibody

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An antigen-binding immunoglobulin, produced by B cells, that functions as the effector in an immune response.

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antigen presentation

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The process by which an MHC molecule cradles a fragment of an intracellular protein antigen in its hammocklike groove, carries it to the cell surface, and "presents" the protein to an antigen receptor on a nearby T cell.

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antigen receptor

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Transmembrane versions of antibody molecules that B cells and T cells use to recognize specific antigens. Also called membrane antibodies.

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antigen-presenting cell (APCs)

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Cells that ingest bacteria and viruses and then destroy them. Class II MHC molecules in these cells collect peptide remnants of this degradation and present them to helper T cells.

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antigen

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A foreign macromolecule that does not belong to the host organism and that elicits an immune response.

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B lymphocyte (B cell)

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A type of lymphocyte that develops in the bone marrow and later produces antibodies, which mediate humoral immunity.

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basophil

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A circulating leukocyte that produces histamine.

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CD4

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A T cell surface protein, present on most helper T cells, CD4 binds to part of the class II MHC protein.

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CD8

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A T cell surface protein that enhances the interaction between the antigen-presenting infected cell and a cytotoxic T cell.

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cell-mediated immunity

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The type of immunity that functions in defense against fungi, protists, bacteria, and viruses inside host cells and against tissue transplants, with highly specialized cells that circulate in the blood and lymphoid tissue.

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chemokine

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A group of about 50 different proteins secreted by blood vessel endothelial cells and monocytes. These molecules bind to receptors on many types of leukocytes and induce numerous changes central to inflammation.

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class I MHC molecules

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A collection of cell surface glycoproteins encoded by a family of genes called the major histocompatibility complex. In humans, these glycoproteins are also known as the HLA, human leukocyte antigens. Class I MHC molecules are found on all nucleated cells.

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class II MHC molecules

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A collection of cell surface glycoproteins encoded by a family of genes called the major histocompatibility complex. In humans, these glycoproteins are also known as the HLA, human leukocyte antigens. Class II MHC molecules are restricted to a few specialized cell types.

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clonal selection

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The mechanism that determines specificity and accounts for antigen memory in the immune system; occurs because an antigen introduced into the body selectively activates only a tiny fraction of inactive lymphocytes, which proliferate to form a clone of effector cells specific for the stimulating antigen.

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complement fixation

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An immune response in which antigen-antibody complexes activate complement proteins.

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complement

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A set of about 20 serum proteins that carry out a cascade of steps leading to the lysis of microbes.

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cytokines

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In the vertebrate immune system, protein factors secreted by macrophages and helper T cells as regulators of neighboring cells.

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cytotoxic T cell (TC)

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A type of lymphocyte that kills infected cells and cancer cells.

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effector cell

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A muscle cell or gland cell that performs the body's responses to stimuli; responds to signals from the brain or other processing center of the nervous system.

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epitope

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A localized region on the surface of an antigen that is chemically recognized by antibodies; also called antigenic determinant.

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graft versus host reaction

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An attack against a patient's body cells by lymphocytes received in a bone marrow transplant.

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heavy chains

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Polypeptide chains that contribute to the structure of an antibody. Two identical heavy chains and two identical light chains, joined by disulfide brides, form a Y-shaped antibody molecule.

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helper T cell (TH)

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A type of T cell that is required by some B cells to help them make antibodies or that helps other T cells respond to antigens or secrete lymphokines or interleukins.

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histamine

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A substance released by injured cells that causes blood vessels to dilate during an inflammatory response.

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HIV (human immunodeficiency virus)

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The infectious agent that causes AIDS; HIV is an RNA retrovirus.

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humoral immunity

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The type of immunity that fights bacteria and viruses in body fluids with antibodies that circulate in blood plasma and lymph, fluids formerly called humors.

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immune adherence

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The collective action of antibodies, complement, and phagocytes. Microbes coated with antibodies and complement proteins adhere to blood vessel walls, making the pathogens easier prey for phagocytic cells circulating in the blood.

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immunization

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Also called vaccination, it is the exposure of an organism to agents that can no longer cause disease but retain the ability to act as antigens, thereby stimulating an immune response and immunological memory.

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immunoglobulin (Ig)

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One of the class of proteins comprising the antibodies.

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inflammatory response

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A line of defense triggered by penetration of the skin or mucous membranes, in which small blood vessels in the vicinity of an injury dilate and become leakier, enhancing the infiltration of leukocytes; may also be widespread in the body.

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interferon

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A chemical messenger of the immune system, produced by virus-infected cells and capable of helping other cells resist the virus.

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interleukin-1 (IL-1)

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A cytokine secreted by a macrophage that is in the process of phagocytizing and presenting antigen. IL-1, in combination with the antigen, activates the helper T cell to produce IL-2 and other cytokines.

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interleukin-2 (IL-2)

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A cytokine that helps B cells that have contacted antigen differentiate into antibody-secreting plasma cells.

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light chains

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Polypeptide chains that contribute to the structure of an antibody. Two identical light chains and two identical heavy chains, joined by disulfide bridges, form a Y-shaped antibody molecule.

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macrophage

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An amoeboid cell that moves through tissue fibers, engulfing bacteria and dead cells by phagocytosis.

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major histocompatibility complex (MHC)

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A large set of cell surface antigens encoded by a family of genes. Foreign MHC markers trigger T-cell responses that may lead to the rejection of transplanted tissues and organs.

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mast cell

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A vertebrate body cell that produces histamine and other molecules that trigger the inflammatory response.

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membrane attack complex (MAC)

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A molecular complex including complement proteins that generates a 7–10 nm diameter pore in a bacterial membrane, causing the cell to die.

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memory cell

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A clone of long-lived lymphocytes, formed during the primary immune response, that remains in a lymph node until activated by exposure to the same antigen that triggered its formation. Activated memory cells mount the secondary immune response.

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monocyte

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An agranular leukocyte that is able to migrate into tissues and transform into a macrophage.

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natural killer (NK) cell

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A nonspecific defensive cell that attacks tumor cells and destroys infected body cells, especially those harboring viruses.

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neutralization

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An immune response in which an antibody binds to and blocks the activity of an antigen.

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neutrophil

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The most abundant type of leukocyte. Neutrophils tend to self-destruct as they destroy foreign invaders, limiting their life span to but a few days.

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opsonization

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An immune response in which the binding of antibodies to the surface of a microbe facilitates phagocytosis of the microbe by a macrophage.

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passive immunity

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Temporary immunity obtained by acquiring ready-made antibodies or immune cells; lasts only a few weeks or months because the immune system has not been stimulated by antigens.

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perforin

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A protein secreted by a cytotoxic T cell that lyses (ruptures) an infected cell by perforating its membrane.

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phagocytosis

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A type of endocytosis involving large, particulate substances.

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plasma cell

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A derivative of B cells that secretes antibodies.

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primary immune response

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The initial immune response to an antigen, which appears after a lag of several days.

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pyrogen

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Molecules that set the body's thermostat to a higher temperature. They are released by certain leukocytes.

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Rh factor

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A category of erythrocyte antigen that generates antibodies of the IgG class.

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secondary immune response

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The immune response elicited when an animal encounters the same antigen at some later time. The secondary immune response is more rapid, of greater magnitude, and of longer duration than the primary immune response.

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T cell receptor

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Antigen receptors on a T cell. Unlike antibodies, T cell receptors are never produced in a secreted form.

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T lymphocyte (T cell)

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A type of lymphocyte responsible for cell-mediated immunity that differentiates under the influence of the thymus.

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T-dependent antigen

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Antigens that can stimulate antibody production only with help from T helper cells. Most protein antigens are T-dependent.

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T-independent antigen

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Antigens that can stimulate antibody production without the help of IL-2.

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tumor antigen

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A foreign macromolecule, associated with a tumor, which does not belong to the host organism and that elicits an immune response.

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vaccination

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A procedure that presents the immune system with a harmless variant or derivative of a pathogen, thereby stimulating the immune system to mount a long-term defense against the pathogen.

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T-independent antigen

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Antigens that can stimulate antibody production without the help of IL-2.

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tumor antigen

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A foreign macromolecule, associated with a tumor, which does not belong to the host organism and that elicits an immune response.

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vaccination

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A procedure that presents the immune system with a harmless variant or derivative of a pathogen, thereby stimulating the immune system to mount a long-term defense against the pathogen.