IS LAB - GLOSSARY

Absorption

a laboratory technique that involves the removal of antibodies by the use of a specific antigen (i.e., red blood cell surface antigen).

Accuracy

the proximity or closeness of a value to the true value.

Acquired

incurred due to external factors and is not inherited.

Acute-phase proteins

normal serum constituents that increase or decrease in the presence of an infection, injury, or trauma to tissues; associated with inflammatory reactions.

Adjuvant

a substance added to vaccines to potentiate or enhance the immune response of the recipient; examples include alum and Freund's adjuvant.

Aldolase

the key enzyme in the glycolytic cycle of Plasmodium parasite.

Adsorption

a process of attachment of one substance to the surface of another; attachment of an antibody to a specific antigen receptor on a cell surface.

Affinity

binding strength between an antigenic determinant (epitope) and its complementary site (paratope) in the Fab region of the antibody.

Agammaglobulinemia

absence of all immunoglobulins in serum.

Agglutination

aggregation or clumping of cellular or particulate antigens to their corresponding antisera containing antibodies.

Agglutinin

an antibody capable of causing agglutination with multivalent surface antigens; usually belongs to IgM class.

Agglutinogen

a particulate or cellular antigen involved in agglutination or aggregation.

Alkaline phosphatase

an enzyme that liberates inorganic phosphates from phosphate esters; used as an indicator label in immunoassays.

Allele

an alternative form(s) of a gene at a particular locus or specific position on a chromosome.

Allergen

an antigen that triggers an allergic or hypersensitivity reaction.

Alum

an adjuvant commonly added to human vaccines.

Amboceptor

an anti-sheep red blood cell antibody that causes hemolysis of sheep red blood cells in the presence of complement.

Anamnestic response

a rapid rise in the immunoglobulin concentration following subsequent exposure to an antigen; also known as a secondary immune response or booster response.

Antibody

an immunoglobulin (Ig) formed in response to an antigen.

Antibody titer

highest dilution factor of a sample that still results in a visible reaction (i.e., agglutination).

Antigen

any substance that, when introduced into the body, stimulates antibody production.

Antigen-antibody complex

union of an antibody with its homologous antigen.

Antigen-presenting cells (APC)

accessory cells present in tissues that process antigens and display fragments on the cell surface in association with a Class Il major histocompatibility complex molecules; examples include dendritic cells and macrophages.

Antigen valency

number of antigenic determinants on an antigen.

Antigenic determinant

a specific region of an antigen that is recognized by the B

Antigenicity

ability of a substance to react with immune products.

Antinuclear antibody (ANA)

an autoimmune antibody directed against a nuclear component; usually seen in patients with systemic lupus erythematosus.

Antistreptolysin O (ASO)

an antibody produced against streptolysin O, a hemolysin produced by group A Streptococcus.

Atypical lymphocytes

suppressor and cytotoxic T-cells capable of recognizing and killing B-cells infected by viruses such as Epstein-Barr virus; also known as reactive lymphocytes.

Australia antigen

former name of the hepatitis B surface antigen.

Autoimmunity

the condition in which an immune response is initiated by "self" antigens.

Avidity

the sum total binding strength between an antigen and an antibody.

B-cell

a lymphocyte that originated from the bone marrow; cells of the adaptive immune response that possess surface antibodies that are specific to an epitope.

C-reactive protein

a protein not normally present in human blood but is present in a wide variety of inflammatory reactions; characterized by their ability to react with the C-polysaccharide component of pneumococci.

Cardiolipin

a substance composed of fresh beef heart extract combined with lecithin and cholesterol.

Cell-mediated immunity

immunity that is dependent on T-cells and phagocytic cells.

Chemotaxis

the movement of cells such as neutrophils toward a stimulus.

Cluster of designation (CD)

cell surface markers that are employed for immunophenotyping cells particularly lymphocytes; also known as cluster of differentiation.

Cold agglutinins

agglutinins that belong to the IgM class and are active at 4°C but not at 37°C.

Complement

a humoral mechanism of non-specific immune responses of at least 14 components that proceed in a cascading sequence of activation, resulting in cell lysis; formerly known as alexin; there are three complement pathways, namely, classical, alternative, and mannose-binding lectin.

Complement fixation

the process of binding of complement in a reaction with an antigen and antibody

Control

a substance that is similar to the patient sample that is used to monitor the precision of analytical tests.

Cytokine

a protein molecule secreted by leukocytes that regulate immune response.

Davidsohn differential test

a hemagglutination test that defines the characteristics of the heterophile antibody through guinea pig and beef cell antigens

Density gradient centrifugation

the most common procedure for the separation of lymphocytes.

Eluate

a fluid containing antibodies deliberately removed from red blood cells.

Enzyme immunoassay

a ligand assay that employs an enzyme label, and the binding reagent is an antibody

Epitope

a specific region of antigen that is recognized by a B-cell or T-cell.

Equivalence point

a point of dilution in a serologic reaction in which there is maximal binding of the antigen and antibody as seen in precipitation reactions.

Febrile agglutinins

agglutinating antibodies that are produced in response to microorganisms that induce fever.

Flocculation

a type of precipitation that occurs over a narrow range of antigen concentration; involves the aggregation of colloidal particles described as a fleecy mass or clump.

Forssman antibody

a heterophile antibody that is found in serum samples of most normal individuals.

Guinea pig kidney antigen

a substance that absorbs Forsmann and serum sickness antibodies.

H-antigens

flagellar antigens

Hapten

a small non-immunogenic molecule that can function as an epitope if bound to a carrier molecule.

Hemagglutination

agglutination of red blood cells

Hemagglutinin

a substance that causes agglutination of erythrocytes.

Hemolysis

rupturing (lysis) of red blood cells and the subsequent release of their contents into the surrounding fluid.

Hemolyzed

ruptured erythrocytes

Heterophile antibodies

antibodies that are produced in an individual in response to an antigen that will also react with another unrelated antigen.

Human immunodeficiency virus (HIV)

A retrovirus that causes disease affecting the immune system; etiologic agent of acquired immunodeficiency disease.

Humoral immunity

adaptive immunity that involves the production of antibodies.

Immune response

a reaction that demonstrates a specific antibody response to an antigen.

Immunity

a condition that is resistant to an infection.

Immunodiffusion

a laboratory method employed for the qualitative or quantitative detection of antibodies.

Immunogen

an antigen capable of stimulating an immune response.

In vitro

outside the body; observable in a test tube

In vivo

within a living organism

Inactivation

the process in which complement activity in a serum is nullified by heating.

Inflammation

the total reaction of a body against an injury or invasion.

K antigen

capsular antigen

Lattice

a structure that forms when a multivalent antigen binds to an antibody in optimal or maximal proportions.

Ligand

a molecule that binds or forms a complex with a biologic molecule such as receptors, proteins, or antibodies

Lysin

an antibody that causes the dissolution of cells.

Major histocompatibility complex

a collection of structural genes that code for proteins that can serve as antigen-presenting molecules in cell-mediated immunity as well as proteins needed in tissue transplantation.

Multivalent

refers to the presence of multiple copies of the same epitope within the same antigen.

Neutralization

an antigen-antibody reaction in which the reactive effect of a particular antigen is nullified by a specific antibody.

Nitroblue tetrazolium test

a qualitative test to determine defects in the NADPH oxidase; employed in the detection of chronic granulomatous disease.

Non-treponemal antibodies

nonspecific antibodies detected in patients with syphilis; examples include reagin and Wasserman antibodies.

O-antigen

somatic antigen

Opsonin

a molecule that attaches itself to microorganisms or antigens to enhance phagocytosis.

Opsonization

the process wherein the antibody coats an antigen to allow a more effective phagocytosis.

Paired sera

serum samples obtained from patients during the acute and convalescent phase; used to determine if there is a significant antibody titer increase.

Panspecific

related to all or every or a large group; a panspecific antibody has a capability of recognizing different isoforms of protein.

Phagocytosis

a process wherein phagocytes, such as neutrophils and macrophages, engulf or "eat" microbes or particulate matter.

Plasma

the fluid matrix of unclotted blood

Postzone reaction

a weak or negative antigen antibody-reaction that occurs when there is an antigen excess in the presence of a relatively low amount of antibody.

Precipitation

an antigen-antibody reaction between a soluble antigen and an antibody that produces an insoluble precipitate.

Precipitin

an antibody that interacts with a soluble antigen; IgG class are usually involved.

Primary tests

tests that involve a specific recognition and interaction of an antigen to its corresponding antibody; examples include enzyme immunoassays and radioimmunoassays; these tests are more sensitive than secondary tests.

Prozone reaction

a weak or negative antigen-antibody reaction that occurs when serum containing antibodies is in excess in the presence of a relatively low amount of antigen.

Radioimmunoassay

an immunologic test that employs radioisotopes as labels for antigens or antibodies, complements, or other reactants.

Reagin

an antibody-like substance produced in response to certain tissue invasion and destruction such as in syphilis.

Rheumatoid factor

an IgM antibody produced in patients with rheumatoid arthritis which binds to the Fc portion of IgG.

Sensitization

a process in which cells, such as red blood cells, are coated with incomplete or blocking antibodies such as IgG; does not result in agglutination.

Serial dilution

a progressively higher dissolution of a substance arranged in a definite sequence or series.

Seroconversion

the detection of a specific antibody in the serum of an individual whose antibody was previously undetectable.

Serology

a branch of biology that deals with the study of antigens and antibodies and their biologic relationships.

Serum

the fluid matrix of clotted blood.

Serum sickness

a type of hypersensitivity reaction that involves the giving of nonhuman gamma globulins for immunization; patients experience fever, rashes, lymphadenopathy, and joint inflammation.