Glossary1


Adaptive immune response

A response to foreign material characterized by specificity and memory that can be promoted by antibody-or antigen-committed lymphocytes.

Allergen

An antigen that provokes an allergic reaction.

Allergy

A clinical manifestation of hypersensitivity; classically defined as antigen-specific altered reactivity of host to antigen.

Alloantigen

An antigen that occurs in some, but not all, members of a species.

Allotype

Any of the alternative characters controlled by allelic genes.

Anaphylaxis

Any life-threatening allergic reaction.

Anergy

Absence of immune reaction to a specific antigen.

Angioedema

Angioneurotic edema. Recurring attacks of transient edema suddenly appearing in areas of the skin or mucous membranes and occasionally of the viscera, often associated with dermatographism, urticaria, erythema, and purpura. In the hereditary form, transmitted as an autosomal dominant trait, it tends to involve more visceral lesions than the sporadic form, especially of the respiratory and gastrointestinal tract. Two types of the familial form have been identified: one involves failure of synthesis of the inhibitor of complement component C1, the

1  

Sources used to compile this glossary include the following:

Dorland's Illustrated Medical Dictionary, 26th ed., W. B. Sanders Co., Philadelphia, 1,485 pp., 1981.

Immunology, I. Roitt, J. Brostoff, and D. Male, Gower Medical Publishing, London, 316 pp., 1985.

International Dictionary of Medicine and Biology, vols. 1 and 2, John Wiley & Sons, New York, 3,200 pp., 1986.

Advanced Immunology, D. Male, B. Champion, and A. Cooke, J.B. Lippincott Co., Philadelphia, 222 pp., 1987.



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Biologic Markers in Immunotoxicology Glossary1 Adaptive immune response A response to foreign material characterized by specificity and memory that can be promoted by antibody-or antigen-committed lymphocytes. Allergen An antigen that provokes an allergic reaction. Allergy A clinical manifestation of hypersensitivity; classically defined as antigen-specific altered reactivity of host to antigen. Alloantigen An antigen that occurs in some, but not all, members of a species. Allotype Any of the alternative characters controlled by allelic genes. Anaphylaxis Any life-threatening allergic reaction. Anergy Absence of immune reaction to a specific antigen. Angioedema Angioneurotic edema. Recurring attacks of transient edema suddenly appearing in areas of the skin or mucous membranes and occasionally of the viscera, often associated with dermatographism, urticaria, erythema, and purpura. In the hereditary form, transmitted as an autosomal dominant trait, it tends to involve more visceral lesions than the sporadic form, especially of the respiratory and gastrointestinal tract. Two types of the familial form have been identified: one involves failure of synthesis of the inhibitor of complement component C1, the 1   Sources used to compile this glossary include the following: Dorland's Illustrated Medical Dictionary, 26th ed., W. B. Sanders Co., Philadelphia, 1,485 pp., 1981. Immunology, I. Roitt, J. Brostoff, and D. Male, Gower Medical Publishing, London, 316 pp., 1985. International Dictionary of Medicine and Biology, vols. 1 and 2, John Wiley & Sons, New York, 3,200 pp., 1986. Advanced Immunology, D. Male, B. Champion, and A. Cooke, J.B. Lippincott Co., Philadelphia, 222 pp., 1987.

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Biologic Markers in Immunotoxicology other involves the synthesis of an abnormal protein. Antibody A protein molecule belonging to the immunoglobulin class of proteins. Antibodies are found in serum and secretions, they are produced by B cells in response to an antigen, and they combine specifically with the antigen. Antibody-dependent, cell-mediated cytotoxicity (ADCC) A phenomenon in which target cells coated with antibody are destroyed by specialized killer cells (K cells), which bear Fc receptors. Antigen Foreign material that can induce an immune response mediated by antibodies or lymphocytes. Antigenic determinant A single antigenic site on a complex antigenic molecule or particle; epitope. Ataxia-telangiectasia Severe progressive cerebellar ataxia, associated with oculocutaneous telangiectasia, sinopulmonary disease with frequent respiratory infections, and abnormal eye movements; it is a hereditary disorder transmitted as an autosomal recessive trait, usually appearing when the child attempts to learn to walk. It is also associated with immunodeficiency (IgA and IgE) and sometimes associated with cell-mediated dysfunction. Atopy A genetic predisposition toward the development of IgE-mediated immediate hypersensitivity reactions against common environmental antigens. Autoantibodies Antibodies produced by a host to its own tissues. Autoimmune disease A disease involving a humoral or cell-mediated immunity to the tissues of one's own body. A failure of the immune system to discriminate between self and nonself. Basophils Circulating polymorphonuclear leukocytes that have a small number of prominent purple or black cytoplasmic granules when stained with dyes that indicate a base pH. The granules contain histamine and chondroitin sulfate. In tissues they are called mast cells. B lymphocytes (B cells) Cells that originate in bone marrow that migrate into blood, lymph, and lymphoid tissue. They express specific surface antibody, which can bind antigen and results in B-cell differentiation into plasma cells. B cells carry immunoglobulin and class II MHC (major histocompatibility complex) antigens on their surfaces. Candidiasis Infection with a fungus of the genus Candida. It is usually a superficial infection of the moist cutaneous areas of the body and is generally caused by C. albicans; it most commonly involves the skin (dermatocandidiasis), oral mucous membranes (thrush, def. 1), respiratory tract (bronchocandidiasis), and vagina (vaginitis). Rarely there is a systemic infection or endocarditis. Carrier A large immunogenic molecule or particle to which an antigenic determinant is attached, allowing the determinant to become immunogenic. CD4 Helper T cells. A cell-surface antigen on T cells having specificity for class II major histocompatibility complex. CD8 Suppressor T cells. A cell-surface antigen on T cells having specificity for class I major histocompatibility complex antigens.

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Biologic Markers in Immunotoxicology Cell-mediated cytotoxicity Killing (lysis) of a target cell by a lymphocyte. Cell-mediated immunity Immune reaction mediated by T cells; in contrast with humoral immunity, which is antibody-mediated. (See also delayed-type hypersensitivity.) Chemotaxis The movement of an organism or an individual cell, such as a leukocyte, in response to a chemical gradient. Chlamydia A genus of the family Chlamydiaceae, order Chlamydiales, occurring as two species that cause a wide variety of diseases in humans and animals. Class I MHC antigens Antigens encoded by the major histocompatibility complex (MHC) of genes that are found on all nucleated cells and are composed of two polypeptide chains of 45 and 12 kilodaltons. Class II MHC antigens Antigens found on antigen-presenting cells and composed of two polypeptide chains of 28 and 32 kilodaltons. Also known as Ia antigens, Complement A family of at least nine normal serum proteins designated C1, C2, etc., that is activated by antigen-antibody complexes, which results in lysis of erythrocytes and bacteria, enhanced phagocytosis, and immune adherence. Contact sensitivity An epidermal reaction characterized by eczema caused when an antigen is applied to previously sensitized skin. Also called contact hypersensitivity. Cross-reactivity The ability of an antibody, specific for one antigen, to react with a second antigen; a measure of relatedness between two antigenic substances. Cytokine A nonantibody protein secreted by one cell of the immune system that mediates a response in other cells. A lymphokine is a type of cytokine. Cytomegalovirus One of a group of highly host-specific herpes viruses that infect humans, monkeys, or rodents, with the production of unique large cells bearing intranuclear inclusions. The virus specific for humans causes cytomegalic inclusion disease, and it has been associated with a syndrome resembling infectious mononucleosis. Also termed salivary gland virus. Cytotoxic T cell A thymus-derived lymphocyte that circulates in search of a target cell, displaying a determinant recognized by its receptor. It must recognize target-cell antigen in association with major histocompatibility complex determinants. Delayed-type hypersensitivity A T-cell-mediated reaction to antigen, which takes 24-48 hours to develop fully and which involves release of lymphokines and recruitment of monocytes and macrophages. Previous exposure is required. Examples include response to Mycobacterium tuberculosis (tuberculin test) and contact dermatitis (poison ivy). Also called cell-mediated immunity. Dendritic A cell type found in spleen and lymph nodes that is involved in antigen presentation and the stimulation of lymphocytes. Eczema A superficial inflammatory process involving primarily the epidermis, characterized early by redness, itching, minute papules and vesicles, weeping, oozing, and crusting, and later by scaling lichenification and often pigmentation. It is not a disease entity or an acceptable diagnosis. Edema The presence of abnormally large

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Biologic Markers in Immunotoxicology amounts of fluid in the intercellular tissue spaces of the body; usually applied to demonstrable accumulation of excessive fluid in the subcutaneous tissues. Edema may be localized and due to venous or lymphatic obstruction or to increased vascular permeability, or it may be systemic and due to heart failure or renal disease. Collections of edema fluid are designated according to the site, e.g., ascites (peritoneal cavity), hydrothorax (pleural cavity), and hydropericardium (pericardial sac). Endocytosis The uptake by a cell of material from the environment by invagination of its plasma membrane; it includes both phagocytosis and pinocytosis. Enzyme-linked immunosorbent assay (ELISA) An assay in which an enzyme is linked to an antibody and a colored substrate is used to measure the activity of bound enzyme and, hence, the amount of bound antibody. Eosinophil A granular leukocyte with a nucleus that usually has two lobes connected by a slender thread of chromatin, and cytoplasm containing coarse, round granules that are uniform in size and stained by eosin. Also called acidocyte, eosinocyte, eosinophilic leukocyte, and Rindfleisch's cell. Epitope Antigenic determinant. Epstein-Barr virus A herpes-like virus that causes infectious mononucleosis and is associated with Burkitt's lymphoma and nasopharyngeal carcinoma. Erythema A name applied to redness of the skin produced by congestion of the capillaries, which may result from a variety of causes, the etiology or a specific type of lesion often being indicated by a modifying term. Fc Fragment of antibody without antigen-binding sites, generated by cleavage with papain; contains the C-terminal domains of the heavy immunoglobulin chains. Fc receptor A receptor on a cell surface with specific binding affinity for the Fc portion of an antibody (immunoglobulin) molecule. Fc receptors are found on many types of cells. Fibrinolytic Pertaining to, characterized by, or causing fibrinolysis, causing breakdown of fiber. Fistula An abnormal passage of communication, usually between two internal organs or leading from an internal organ to the surface of the body; frequently designated according to the organs or parts in communication, as anovaginal, bronchocutaneous, hepatopleural, pulmonoperitoneal, rectovaginal, urethrovaginal, and the like. Such passages are frequently created experimentally for the purpose of obtaining body secretions for physiologic study. Gastroenteritis Inflammation of the stomach and intestines. Gastroenteropathy Any disease of the stomach or intestines. Glomerulonephritis A variety of nephritis characterized by inflammation of the capillary loops in the glomeruli of the kidney. It occurs in acute, subacute, and chronic forms and may be secondary to hemolytic streptococcal infection. Evidence also supports possible immune or autoimmune mechanisms. Granuloma A tumor-like mass or nodule of granulation tissue, with actively growing fibroblasts and capillary buds, consisting of a collection of modified macrophage resembling epithelial cells (epithelioid cells), surrounded by a rim of giant multinucleate

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Biologic Markers in Immunotoxicology cells, either of the Langerhans' or foreign body type; it is due to a chronic inflammatory process associated with infectious disease, such as tuberculosis, syphilis, sarcoidosis, leprosy, lymphogranulma, etc., or with invasion by a foreign body. HLA complex Human leukocyte antigen complex, the major human histocompatibility complex situated on chromosome 6; contains several subregions, called A, B, C, etc. Haplotype The group of alleles of linked genes contributed by either parent; the haploid genetic constitution contributed by either parent. Hapten A compound, usually of low molecular weight, that is not itself immunogenic, but that, after conjugation to a carrier protein or cells, becomes immunogenic and induces production of antibody, which can bind the hapten alone in the absence of carrier. Helper T cells A functional subclass of T cells that help generate cytotoxic T cells and cooperate with B cells in the production of an antibody response. Helper T cells usually recognize antigen in association with class II major histocompatibility complex molecules and bear CD4 markers. Hemolytic anemia Decreased hemoglobin in the blood with a decrease in red blood cells and in the volume of packed red blood cells resulting from abnormal destruction of red blood cells in the body. Herpes simplex An acute viral disease marked by groups of vesicles, each vesicle about 3-6 mm in diameter, on the skin, often on the border of the lips or the nares (h. labialis, cold sores), or on the genitals (h. genitalis). It often accompanies fever (h. febrilis, fever blisters), although there are other precipitating factors, such as the common cold, sunburn, skin abrasions, and emotional disturbances. Histamine 4-(2-Aminoethyl)-imidazole, C5H9N3, an amine occurring as a decomposition product of histidine that stimulates visceral muscles, dilates capillaries, and stimulates salivary, pancreatic, and gastric secretions. It is found in the granules of the basophils and mast cells responsible for anaphylactic reactions. Humoral immunity An immune reaction that can be transferred with immune serum (as opposed to cell-mediated immunity). In general, refers to resistance that results from the presence of a specific antibody. Hypersensitivity An adaptative immune response against an antigen that occurs in an exaggerated or inappropriate form and that can lead to tissue damage. Four types of hypersensitivity are recognized. (See allergy.) Hypersensitivity pneumonitis Allergic alveolitis. Ia antigen Immune-associated surface antigen of mouse cells, such as B lymphocytes and macrophages, that is determined by the major histocompatibility complex II system. IL-1 (interleukin-1) An acute-phase reactant synthesized by many cell types, including monocytes and lymphocytes. This hormone has many effects, including the activation of resting T cells, the promotion of synthesis of other lymphokines, and the activation of macrophages and endothelial cells. Also an endogenous inducer of fever. IL-2 (interleukin-2) Soluble substance released

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Biologic Markers in Immunotoxicology by T cells through the synthesis of other lymphokines to promote proliferation of other T cells (also called TCGF, T-cell growth factor). IL-3 (interleukin-3) A multilineage colony-stimulating factor released by T cells that appears to act synergistically with granulocyte-macrophage colony-stimulating factor to stimulate hematopoiesis. It is also a growth factor for mast cells. IL-4 (interleukin-4) A growth factor for B cells that induces expression of class II major histocompatibility complex antigen on their surfaces. This hormone also enhances the cytolytic activity of cytotoxic T cells and is a mast cell growth factor. Also known as B-cell-stimulating factor type 1. IL-6 (interleukin-6) Also known as B-cell-stimulating factor type 2 or B-cell differentiation factor, it induces the differentiation of activated B cells into immunoglobulin-secreting plasma cells. Immune complex The product of an antigen-antibody reaction that also can contain components of the complement system. Immunodeficiency A defect or absence of some component of the immune system, e.g. immunoglobulin or T cells, that may result in the inability of the host to eliminate or neutralize foreign substances. Immunofluorescence A method of determining the location of antigen (or antibody) in tissue by the pattern of fluorescence resulting when the tissue is exposed to the specific antibody (or antigen) labeled with a fluorochrome. Immunogen A substance that can induce an immune response and react with the products of an immune response. Compare with antigen. Immunoglobulin (Ig) The protein classes that contain antibody. Each Ig moleculeis made up of two or more heavy chains and two or more light chains and has two or more antigen-binding sites. Immunologic memory A phenomenon characterized by the presence in the body of an expanded set of clonally derived antigen-specific lymphocytes that can be rapidly recruited to produce an augmented immune response on subsequent exposure to the specific antigen. Immunopotentiation An increase in the functional capacity of the immune response. Immunosuppression A reduction in the functional capacity of the immune response caused by drugs prepared with the express purpose of suppressing the immune system. Immunosurveillance The mechanisms by which the immune system recognizes and destroys malignant cells before the formation of an overt tumor. Interferon Proteins that are formed by animal cells in the presence of a virus, that prevent viral reproduction, and that can induce resistance to a variety of viruses in fresh cells of the same animal species. There are three classes: alpha, beta, and gamma. Alpha interferon (IFNα) is made by lymphocytes and macrophages. Beta interferon (INFβ) is synthesized by fibroblasts and epithelial cells. Alpha and beta interferons were once called type 1 interferon. Gamma interferon (IFNγ), also called type 2 interferon, is synthesized by lymphocytes. All three interferons can be induced during viral infection. They have antiviral and antiproliferative effects, and all induce expression of major histocompatibility complex I antigens.

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Biologic Markers in Immunotoxicology K cell A lymphocyte with Fc receptors that allow it to bind to and kill antibody-coated target cells. Killer T cell A T cell with a particular immune specificity and an endogenously produced receptor for antigen that can kill its target cell after attachment to the target cell by this receptor. Also called cytotoxic cell. Kinin Any of a group of endogenous peptides that cause vasodilation, increase vascular permeability, cause hypotension, and induce contraction of smooth muscle. Langerhans cells Stellate, dendritic cells of the mammalian skin thought to be of the melanocyte series. They are strongly positive for class II MHC antigen. Lymphocyte Small cell with virtually no cytoplasm, found in blood, in all tissue, and in lymphoid organs, such as lymph nodes, spleen, and Peyer's patches. Lymphocyte-activating factor Interleukin-1. Lymphokines Soluble substances secreted by lymphocytes that have a variety of specific and nonspecific effects on other cells. A generic term for molecules other than antibodies that are involved in signaling between cells of the immune system and are produced by lymphocytes (cf. interleukins). Lymphoma Any neoplasm, usually malignant, of the lymphatic tissues. Lymphopenia A reduction in the number of circulating lymphocytes. Also called lymphocytopenia. Lymphopoiesis Production of lymphocytes. Lyse To cause or produce disintegration of a compound, substance, or cell. Macrophage Mononuclear cell derived from bone marrow and found in blood (where it is known as the monocyte), lymph, and many organs. Two main functions are recognized: phagocytosis and antigen presentation. Major histocompatibility complex (MHC)A cluster of genes encoding cell-surface antigens that are polymorphic within a species and that code for antigens that lead to rapid graft rejection between members of a single species that differ at these loci. They also function in signaling between lymphocytes and cells expressing antigen. Several major classes of protein, such as MHC class I and II proteins, are encoded in this region. Mast cell A small cell similar in appearance to a basophil and found associated with mucosal epithelial cells. These cells depend on T cells for proliferation, and they contain cytoplasmic granules laden with heparin, slow-reactive substance of anaphylaxis, and eosinophil chemotactic factor of anaphylaxis, which are released when antigen binds to membrane-bound IgE. Mitogen A substance that nonspecifically stimulates the proliferation of lymphocytes and other cells. Monoclonal Literally, coming from a single clone. A clone is the progeny of a single cell. In immunology, "monoclonal" generally describes a preparation of antibody that is homogeneous, or cells of a single specificity. Monocyte A mononuclear phagocytic leukocyte, 13-25 µm in diameter, with an ovoid or kidney-shaped nucleus, containing lacy, linear, chromatin, and abundant gray-blue cytoplasm filler with fine, reddish and azurophilic granules. Formed in the bone marrow from the promonocyte, monocytes are transported to tissues, as of the

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Biologic Markers in Immunotoxicology lung and liver, where they develop into macrophages. Formerly called large mononuclear leukocyte and hyaline or transitional leukocyte. Mucocutaneous Pertaining to or affecting the mucous membrane and the skin. Myelopoiesis The process of formation and development of blood cells in the bone marrow. Natural killer cell (NK cell) A lymphocyte that can destroy nonspecifically certain virally infected and tumor cells. Neoantigen A tumor-specific antigen. Neutropenia A decrease in the number of neutrophilic leukocytes in the blood. Neutrophils Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin and cytoplasm containing fine inconspicuous granules. Neutrophils have the properties of chemotaxis, adherence to immune complexes, and phagocytosis. Called also polymorphonuclear, polynuclear, or neutrophilic leukocytes. Their counterparts in nonhuman mammals are heterophils. Any cell, structure, or histologic element readily stainable by neutral dyes. Null cells A population of lymphocytes bearing neither T-cell nor B-cell differentiation antigens. Opsonizing The process by which bacteria are altered by the attachment of antibody so that they are more readily and more efficiently engulfed by phagocytes. Periodontitis Inflammatory reaction of the tissues surrounding a tooth (periodontium), usually resulting from the extension of gingival inflammation (gingivitis) into the periodontium. PFC (plaque-forming cell) An antibody-secreting B cell that can be recognized by the production of a hemolytic plaque. Phagocytosis The ingestion of foreign material, for example, by a macrophage, into a cell. Plasma cell A terminally differentiated B lymphocyte that can synthesize and secrete antibody. Pneumonitis Inflammation of the lungs. Polyarteritis nodosa Inflammation of several arteries with the formation of numerous nodules within the walls of the arteries. (Also referred to as periarteritis or panarteritis.) Polymorph A phagocytic polymorphonuclear leukocyte. Polymorphonuclear leukocyte The mature neutrophil leukocyte, so-called because of its segmented and irregularly shaped nucleus. Primary response The immune response to a first encounter with antigen. The primary response is generally small, has a long induction phase or lag period, consists primarily of the release of IgM antibodies, and generates immunologic memory. ProperdinA relatively heat-labile, normal serum protein (a euglobulin) that, in the presence of complement component C3 and magnesium ions, acts nonspecifically against gram-negative bacteria and viruses and plays a role in lysis of erythrocytes. It migrates as a β-globulin and, although not an antibody, may act in conjunction with complement-fixing antibody. Prostaglandin E-2 An unsaturated fatty acid, 20 carbons long, with an internal

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Biologic Markers in Immunotoxicology cyclopentane ring. It causes vasodilation, inhibits gastric secretion, induces labor and abortion, and is immunosuppressive. A derivative of arachidonic acid. Radioallergosorbent test (RAST) A solidphase radioimmunoassay for detecting IgE antibody specific for a particular allergen. Raynaud's phenomenon Intermittent bilateral attacks of ischemia of the fingers or toes and sometimes of the ears and nose, marked by a severe pallor and often accompanied by paresthesia and pain; it is brought on characteristically by cold or emotional stimuli and relieved by heat and is due to an underlying disease or anatomic abnormality. When the condition is idiopathic or primary, it is termed Raynaud's disease. Recall antigen Material recognized by ''memory" cells that stimulates rapid (secondary) immune responses. Rhinitis Inflammation of the mucous membrane of the nose. Sarcoidosis A chronic, progressive, generalized granulomatous reticulosis of unknown etiology, involving almost any organ or tissue, including the skin, lungs, lymph nodes, liver, spleen, eyes, and small bones of the hands and feet. It is characterized histologically by the presence in all affected organs or tissues of noncaseating epithelioid cell tubercles. Laboratory findings may include hypercalcemia and hypergammaglobinemia; there is usually diminished or absent reactivity to tuberculin, and in most active cases, a positive Kveim reaction. The acute form has an abrupt onset and a high spontaneous remission rate, whereas the chronic form is insidious in onset and progressive. SDS gel electrophoresis A form of polyacrylamide gel electrophoresis that uses sodium dodecyl sulfate (SDS) in the buffer. Self antigen Antigenic component of an individual's tissues. Normally self surface markers are recognized by the immune system neonatally and immunologic tolerance develops. Serotonin 5-Hydroxytryptamine which is present in many tissues, especially blood and nervous tissue. It stimulates a variety of smooth muscles and nerves and is postulated to function as a neurotransmitter. Sjögren's syndrome A symptom complex of unknown etiology, usually occurring in middle-aged or older women, marked by keratoconjunctivitis sicca, xerostomia, and enlargement of the parotid glands; it is often associated with rheumatoid arthritis and sometimes with systemic lupus erythematosus, scleroderma, or polymyositis. An abnormal immune response has been implicated. SLE (systemic lupus erythematosus) An autoimmune disease of humans usually involving antinuclear antibodies and characterized by skin rash, hematologic alterations, and glomerulonephritis. SRBC (sheep red blood cell) A T-cell-dependent target antigen often used in hemolytic plaque assays of immune responsiveness. Stem cell Pluripotent cell that can serve as a progenitor cell for the lymphoid lineage or the myeloid lineage or both (hemopoietic stem cell). Suppressor T cell A subpopulation of T lymphocytes that act to reduce the immune responses of other T or B cells. Suppression can be antigen-specific, idiotype-specific,

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Biologic Markers in Immunotoxicology or nonspecific under different circumstances. Cells with this function cannot be identified with one marker, although many appear to carry the CD8 molecule. Thrombocytopenia Decrease in the number of blood platelets. Thymus An organ in the thoracic or cervical region of mammals, composed of lymphatic tissue in which minute concentric bodies, the remnants of epithelial structures, or thymic corpuscles, are found. This organ is necessary for the development of thymus-derived lymphocytes and is the source of several hormones involved in T-cell maturation, for example, thymosin, thymopoietin, thymulin, and thymocyte humoral factor. Thymus-dependent antigen An antigen that requires an immune response from thymus-derived lymphocytes to elicit an immune response from B lymphocytes. Thymus-independent antigen An antigen that does not require the participation of T lymphocytes to elicit an immune response in B cells. T lymphocytes (T cells) Cells that originate in bone marrow, mature in the thymus, and then migrate into blood, lymph, and lymphoid tissue. They express nonimmunoglobulin antigen receptors and are derived functionally into helper, suppressor, and cytotoxic subpopulations. Transferrin Serum β-globulin that binds and transports iron. Several types (e.g., C, B, and D) have been distinguished on the basis of electrophoretic mobility and related as the products of corresponding dominant somatic genes, TfC, TfB, and TfD. Urticaria A vascular reaction of the skin marked by the transient appearance of smooth, slightly elevated patches (wheals), which are redder or paler than the surrounding skin and often attended by severe itching. The eruption rarely lasts longer than 2 days, but may exist in a chronic form. Certain foods (e.g., shellfish), drugs (e.g., penicillin), infections, or emotional stress may be the exciting cause. Varicella zoster Chickenpox. Wiskott-Aldrich syndrome A condition characterized by chronic eczema, chronic suppurative otitis media, anemia, and thrombocytopenic purpura; it is an immunodeficiency syndrome transmitted as an X-linked recessive trait, in which there is poor antibody response to polysac-charide antigens and dysfunction of cell-medicated immunity. Xenobiotic A chemical from a nonbiologic source.