Vocabulary List #2
affinity A term derived from the Law of Mass
Action. It expresses the strength of binding between
reactants in a reversible reaction.
agglutination The clumping of particulate antigens
by antibody.
allotype The protein product of an allele which
may be detectable as antigen by another member of the same
species.
antiglobulin test A technique for detecting the
presence of nonagglutinating antibody on the surface of a
particle. This is also called a Coombs' test.
antiserum Serum containing specific
antibodies.
avidity The functional combining strength of an
antibody with its antigen which is based on both affinity
and valences of the antibody. Some authors use this term to
describe the increased affinity that occurs as result of
multiple antigen binding sites on an immunoglobulin. Others
use it to describe the strength of binding of a serum with a
complex antigen, while others use it to indicate the rate of
reaction between antigen and antibody. [A good candidate
term for the scrap-heap, yet there is a core concept
involved which is important.]
BALT Bronchial associated lymphoid tissue; part of
MALT.
class A general term referring to an isotype of
antibody; determined by the constant domains of the heavy
chain.
clonal selection The process of lymphocyte
selection and activation in which antigen stimulates only
those cells with specific receptors for the antigen.
clone A family of cells descended from one
"parent" cell; all are genetically identical.
clonotype A B or T cell of a single antigenic
specificity.
constant region The invariant parts of
immunoglobulin heavy and light chains.
cross-reactivity The reaction of antibody with an
unrelated antigen, caused by the antigens involved sharing
epitopes in common.
cytophilic antibody Immunoglobulin that has the
ability to bind spontaneously to cellular Fc receptors.
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domain A discrete structural region within an
immunoglobulin molecule; contains one disulfide bond and a
distinct tertiary structure.
electrophoresis The separation of the proteins in
a complex mixture by subjecting them to an electrical
potential.
ELISA Enzyme-linked immunosorbent assay. An
immunologic test that uses enzyme-linked antiglobulins and
substrate bounds to the walls of polystyrene wells.
epitope An area on the surface of an antigenic
molecule that stimulates a specific immune response and
against which that response is directed. Synonymous with
antigenic determinant.
exon A segment of DNA that contains expressed
genes.
F(ab')2 A fragment of immunoglobulin
resulting from pepsin digestion; consists of N-terminal
halves of heavy chains and whole light chains and a portion
of the hinge region. The valence is 2.
Fab Fragment of antibody. That part of the
immunoglobulin consisting of the N-terminal half of the
heavy chain and its associated light chain; results from
papain digestion. The valence is 1.
FACS Fluorescence activated cell sorter. Cells
labeled with fluorochrome tagged antibodies are separated or
identified by the fluorescent signature given when activated
by the appropriate wavelength of light. Can be used for
quantitative analysis or for purification of a target
population.
Fc Fragment crystallizable. That part of the
immunoglobulin consisting of the C-terminal half of the
heavy chains, containing the constant domains. This portion
determines the isotype of the molecule.
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fluorescence The emission of low energy light at a
higher wavelength when a substance is irradiated with high
energy light of a lower wavelength.
GALT Gut associated lymphoid tissue; part of
MALT.
gel diffusion An immunoprecipitation technique
that involves letting the reactants meet and precipitate in
a clear gel such as agar.
haplotype The complete set of alleles at all loci
within a gene complex on a single chromosome.
hapten A small molecule that cannot initiate an
immune response unless first bound to an immunogenic carrier
molecule. However, once a response is initiated, a hapten
can react specifically with its antibody.
heavy chain The larger of the two types of chains
making up an immunoglobulin molecule; consisting of one
variable domain and three to four constant domains.
hemagglutination The agglutination of red blood
cells.
hemolysin An antibody capable of bonding to red
blood cells and causing their lysis by activation of
complement.
hinge The region between the first and second
constant domains in an immunoglobulin molecule. This part
allows flexibility between the Fab regions; it is also
vulnerable to enzymatic attack.
hypervariable Small segments with immunoglobulin
variable regions where great variations in amino acid
sequence occur.
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idiotype The antigenic characteristic of the
variable region of an immunoglobulin.
immunodiffusion Another name for the gel diffusion
technique.
immunodominant The epitope on a molecule that
provokes the most intense immune response.
immunoelectrophoresis (IEP) A procedure involving
sequential electrophoresis and immunoprecipitation; it is
used to identify the proteins in a complex solution such as
serum.
immunofluorescence Immunologic tests that make use
of antibodies chemically conjugated with a fluorescent dye
such as fluorescein isothiocyanate.
immunogenicity The ability of a substance to
elicit an immune response.
immunoperoxidase Immunologic tests that make use
of antibodies chemically conjugated with the enzyme
peroxidase.
immunoprecipitation The production of precipitate
out of a clear solution by the combination of antigen and
antibody.
incomplete antibody An antibody that can bind to a
particulate antigen but is incapable of causing its
agglutination.
intron A segment of DNA that is inserted between
exons and that does not contain expressed genes. Introns are
transcribed into RNA but are not translated into
protein.
isotype The types of immunoglobulin molecules
common to all members of a species.
J chain A short peptide that joins two monomeric
units into polymeric immunoglobulins. light chain The
smaller of the two types of immunoglobulin chains; consists
of one variable domain and one constant domain.
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MALT Mucus associated lymphoid tissue.
monoclonal antibody Immunoglobulin formed from a
cloned population of cells.
monomer One unit of immunoglobulin; consists of
two light chains and two heavy chains.
neutralization Blockage of the activity of an
organism or a toxin by antibody.
opsonin A substance that facilitates the
phagocytosis of foreign particles.
paratope The antigen binding site of an
immunoglobulin.
passive agglutination The agglutination of inert
particles by antibody directed against antigen bound to
their surface.
polymer Multiple units of immunoglobulin to form a
unique functional unit.
polymorphism Inherited structural differences
between proteins from allogeneic individuals. A form of
allotypic variation.
private antigen An epitope that is restricted to
the product of a specific allele.
prozone The inhibition of agglutination by the
presence of high concentrations of antibody.
pseudogene Genes that have a structure similar to
those of other genes but which cannot be expressed.
public antigen An epitope common to several
distinct gene products.
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radioimmunoassay (RIA) An immunologic test that
requires the use of an isotope-labeled reactant.
serology The science of antibody detection.
somatic mutation Gene rearrangements occurring in
somatic cells rather than germline cells.
specificity A term that describes the ability of a
test to give true positive reactions.
splice The joining of two DNA or RNA segments
together.
subclass Now synonymous with isotype. Subdivisions
of the immunoglobulin classes.
Svedburg unit (S) A measure of the sedimentation
velocity of a molecule. It is determined by several factors,
including molecular weight.
titer The reciprocal of the highest dilution of a
serum that gives a reaction in an immunological test.
titration The measurement of the level of specific
antibodies on a serum by testing increasing dilutions of the
serum for antibody activity.
variable region That part of the immunoglobulin
peptide chains where the amino acid sequence shows
significant variation between molecules.
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