Immunology Glossary
Intervet/Schering-Plough Animal Health
| Wednesday, April 01, 2009
Active immunity – Immunity acquired through exposure to antigen and response of one’s own immune system.
Adaptive immunity - Immunity acquired through responses of antigen-specific lymphocytes, resulting in immune memory.
Adjuvant - A substance added predominantly to killed vaccines to stimulate a better immune response by the body.
Anergy - Lack of immune response.
Antibodies – Any of a large number of proteins of high molecular weight that are produced normally by specialized B cells after stimulation by an antigen. They act specifically against the antigen in an immune response and typically consist of four subunits, including two heavy chains and two lights chains. Also called immunoglobulin (Ig).
Antigen – Any substance (as an immunogen or a hapten) foreign to the body that evokes an immune response either alone or after forming a complex with a larger molecule (as a protein) and that is capable of binding with a product (as an antibody or T cell) of the immune response; specifically: IMMUNOGEN.
Antitoxins - A particular kind of antibody produced in the body in response to the presence of a toxin or toxoid. Most commonly used in the treatment of diseases caused by clostridial toxins.
Attenuated vaccine - Vaccine that uses live but weakened organism to induce immunity.
Autoimmunity - Immune response made against self antigens.
B cell – Lymphocyte that develops in the bone marrow and binds antigen with membrane antibody (immunoglobulin). B cells are involved in humoral immunity.
“Booster” dose - An amount of immunogen or vaccine, sometimes smaller than the original amount, injected at an appropriate interval after primary immunization to enhance and sustain the immune response.
Cell-mediated immunity (CMI) – Immunity resulting from all parts of the immune system being activated by a vaccine (cell-mediated immune response). It involves the activity of T helper 1 cells, T helper 2 cells, cytotoxic T-cells and gamma delta T cells.
Circulating maternal antibodies – Antibodies in the female parent that are produced by clonal B cells and specifically respond to only one antigen.
Cytokine - Small molecule secreted from one cell that signals another cell by binding to its specific receptor.
Cytotoxic - T cell which kills virus-infected cells and tumor cells.
Dendritic cell – Macrophage-like cells with long, filamentous processes located in the cortex of lymph nodes and the skin. Important in antigen trapping, processing and presentation.
Duration of Immunity - The length of immunity. Time protection against disease occurs in response to vaccine exposure.
Efficacy - Intrinsic activity; equal to the magnitude of the maximal response; effectiveness in ability to produce the necessary or desired results.
ELISA - Enzyme-Linked ImmunoSorbent Assay. A type of primary binding test used to detect and measure either antigen or antibody.
Endotoxin - Toxin that is part of the bacterial structure. Usually refers to lipopolysaccharide (LPS) in the gram negative outer membrane.
Epidemiology - Study of disease transmission.
Follicle - In immunology, an area of the spleen or lymph node occupied by B cells and
Gamma Delta T-cells – One of two types of T cells. Composed of gamma and delta chains instead of the more common
alpha and beta chains. They promote wound repair and may represent a first line of defense against invading pathogens.
Gram-negative – Description of bacteria that is decolorized by alcohol in Gram’s method of staining and is thus stained only with the counter stain (usually red). Gram-negative bacteria have a much thinner layer of peptidoglycan in the cell wall than Gram-positive bacteria.
Gram-positive – Description of bacteria that resist decolorization by alcohol in Gram’s method of staining and thus retain the crystal violet-iodine complex and appear purple; a characteristic of bacteria whose cell wall is composed of a thick layer of peptidoglycan and teichoic acid.
Helper T cell - Regulatory T cell that uses cytokines to stimulate B cells to produce antibodies, macrophages to become activated, or cytotoxic T cells to become effector cytotoxic T lymphocytes (
Humoral Immunity - Immunity that can be transferred from one individual to another with serum (i.e., antibody formation).
Immune complex - Non-covalently bound complex of antibody with antigen; disease plus antibody. Plays a role in some types of immune responses.
Immune deficiency - Congenital or acquired inability of the immune system to function correctly, usually due to lack of a molecule or cell.
Immune response - A bodily response to an antigen that occurs when lymphocytes identify the antigenic molecule as foreign and induce the formation of antibodies and lymphocytes capable of reacting with it and rendering it –harmless – also called immune reaction.
Immunogen – Any molecule or antigenic material that can induce an immune response.
Immunoglobulin – An antibody; serum protein that binds to antigen and facilitates its removal. Most common form is IgA.
Immunology - A science that deals with the immune system and the cell-mediated and humoral aspects of immunity and immune responses.
Inactivated vaccine/killed vaccine - Vaccine composed of killed pathogen.
Incubation period - The time between the exposure to a disease-causing agent and the onset of signs of the disease.
Innate Immunity - Immunity present from birth and not dependent on prior antigen exposure. Innate immunity includes physical and chemical barriers to infection.
Interleukin - A cytokine produced by one leukocyte and acting on another.
Intramuscular (IM) - Route of vaccine administration; into the muscle (IM).
Intranasal - Into the nose. One route of modified-live vaccine administration.
Killed vaccine - Vaccines which are made by taking the real, disease-causing virus (or bacteria), killing them, and putting them into a liquid base.
Latent infection - A dormant stage of disease; the patient is infected with an organism but is not yet ill.
Leukocyte - White blood cell; chief function is to protect the body against microorganisms that cause disease.
Leukotoxin - A toxin that destroys leukocytes (white blood cells).
Lymphocyte - Leukocyte that has specific receptors for antigen and participates in adaptive immunity.
Macrophage - Phagocytic white blood cell found in the tissues; the circulating form of the cell is called a monocyte. Acts as an antigen-presenting cell.
Maternally derived antibodies – Antibodies that are transferred from the mother to the newborn to protect it until its immune system is built up enough to protect it.
Memory cell - Lymphocyte that can respond more quickly and efficiently to antigen than a naïve lymphocyte.
Memory response - Repeat response to an antigen that is faster and larger than a primary response.
Modified-live vaccine - Vaccines that are made by taking the real, disease-causing virus and altering (attenuating) it in a laboratory to a non-disease causing virus.
Monoclonal antibody – Antibody that is homogeneous, every molecule identical to the next in physical structure and antigen
binding; produced by a hybridoma. Used to describe cells or products of cells that are formed or derived from a single clone.
Mucosal-Associated Lymphoid Tissue (MALT) – Aggregations and organized lymphoid cell tissue found immediately beneath mucous membranes lining the respiratory, gastrointestinal and urogenital system.
Mucosal immune system – Consists of molecules, cells, and organized lymphoid structures intended to provide immunity to pathogens that impinge upon mucosal surfaces.
Onset of Immunity (OOI) - The beginning of immunity.
Parenteral vaccination – A vaccination not received through the alimentary canal but rather a subcutaneous, intramuscular or intravenous injection.
Passive immunity – The transfer of antibodies from a donor in which they were produced to a recipient for temporary immunity. This can be in the form of serum or colostrum.
Passive immunization - Immunization using pre-formed antibody from another individual. The immunity may be natural, as in the transfer of maternal antibody to off-spring, or artificial, passive immunity following inoculation of antibodies or immune cells.
Pathogen - Disease-causing organism.
Pathological / pathology - The branch of veterinary science that deals with the essential nature of disease, especially of the changes in body tissues and organs that cause or are caused by disease.
Phagocyte – Cell in the bloodstream and tissues that removes unwanted substances.
Phenotype - Genetic characteristics expressed by the cell or organism.
Plasma - Fluid part of the blood containing all proteins, including clotting factors.
Plasma cell - White blood cell that synthesizes and secretes antibody.
Primary immunization - The first vaccination or first set of immunizations.
Primary response - Initial adaptive immune response to an antigen.
Recombinant vaccine - Vaccine made by putting desired pathogen genes into a vector.
Secondary response - Repeat immune response to an antigen; memory response.
Seronegative – Showing a negative serum reaction; uninfected.
Serotype - Antigenic specificity of a pathogen.
Subcutaneous (Sub-Q) - Route of vaccine administration; under the skin; often called ‘sub Q.’
Suppressor T cell - T cell that inhibits the function of B cells or other T cells.
Systemic immune system – The nature of the immune system that allows it to not be confined to the initial infection site but work throughout the body.
T cell – A white blood cell lymphocyte that has developed in the thymus and is essential for various aspects of immunity, especially in combating viral infections. T cells are either helper (CD4) or cytotoxic (CD8) phenotype.
T cell activation - Biochemical process of stimulating a resting T cell to become an effector cell.
T effector cell – Includes large granular lymphocyte; also called natural killer cell and cytotoxic T lymphocytes.
T helper 1 cells - They produce cytokines that promote cellular immune responses.
T helper 2 cells - They produce interleukins 2, 4, 6 and 10, all of which prompt B cells to produce antibodies.
T-dependent antigen - Antigen that generates T cell help for B cells.
T-independent antigen - Antigen that stimulates B cell directly without T cell help.
Titer - Quantification of antibody, often expressed as the highest dilution to give a positive response.
Toxoid - A toxin treated by heat or chemical agent to destroy its harmful properties without destroying its antigenicity. Most clostridial diseases are controlled by vaccination with toxoids. Inactivated toxin, often used as a vaccine against the toxin.
Vaccine – Antigen used for deliberate exposure and induction of protective immunity.
Virology - A branch of science that deals with viruses and viral diseases.
