Labeled Immunoassay

Question 1

Labeled immunoassays are designed
for antigens and antibodies that may be
_________ in size or present in _______.

Answer 1

small in size
very low concentrations

Question 2

The presence of such antigens or
antibodies is determined indirectly by using
a ______ to detect whether or not
specific binding has taken place.

Answer 2

labeled reactant

Question 3

substance to be measured

Answer 3

ANALYTE

Question 4

Examples of analytes

Answer 4

Examples include bacterial and
viral antigens, hormones, drugs, tumor
markers, specific immunoglobulins,
and many other substances.

Question 5

all the reactants are mixed together
simultaneously

Answer 5

Competitive Immunoassay

Question 6

In Competitive Immunoassay the amount of bound label is ______ proportional to the
concentration of the labeled antigen

Answer 6

inversely proportional

Question 8

Typically, an antibody, often called capture antibody, is first passively absorbed to a solid phase

Answer 8

Noncompetitive Immunoassay

Question 9

In Noncompetitive Immunoassay, a ___ is added to the reaction after washing

Answer 9

second antibody with a label

Question 10

In Noncompetitive Immunoassay, the amount of label measured is ____ proportional to the amount of patient antigen

Answer 10

directly proportional

Question 11

requires a step to physically separate free from bound analyte

Answer 11

Heterogeneous Immunoassay

Question 12

no separation step is necessary

Answer 12

Homogeneous Immunoassay

Question 13

Examples of solid-phase vehicle for separation

Answer 13

Polystyrene test tubes

Glass or polystyrene beads

Microtiter plates

Magnetic latex beads

Nitrocellulose membranes

Question 14

The last step common to all immunoassays

Answer 14

detection of the labeled analyte

Question 15

pioneered the first type of immunoassay

Answer 15

Yalow and Berson

Question 16

It was used to determine the level of insulin anti-insulin complexes in diabetic patients

Answer 16

radioimmunoassay (RIA)

Question 17

Used as a label in radioimmunoassay (RIA)

Answer 17

radioactive substance

Question 18

Radioactive elements have nuclei that ______, emitting ___ and ____

Answer 18

decay spontaneously

matter and energy

Question 19

the most popular radioactive label and has a half-life of 60 days

Answer 19

125 I

Question 20

125I is easily incorporated into protein molecules, and it emits ______, which is detected by a ________

Answer 20

gamma radiation

gamma counter

Question 21

RIA was originally based on the principle of

Answer 21

competitive binding

Question 22

Used to measure total IgE

Answer 22

Radioimmunosorbent Assay (RIST)

Question 23

Used to measure IgE to specific allergens

Answer 23

Radioallergosorbent Assay (RAST)

Question 24

Radioimmunoassay

DISADVANTAGES

Answer 24

• Problems with disposal

• Short shelf-life of labels

• There is the need for expensive equipment

Question 25

are naturally occurring molecules that catalyze certain biochemical reactions

Answer 25

Enzymes

Question 26

Enzymes react with suitable substrates to produce breakdown products that may be

Answer 26

chromogenic, fluorogenic, or luminescent

Question 27

Typically used enzymes

Answer 27

Alkaline phosphatase

Horseradish peroxidase

Glucose-6-phosphate dehydrogenase

β-D-galactosidase

Question 28

Most often used; highest turnover, high sensitivity, easy to detect enzymes

Answer 28

Alkaline phosphatase

Horseradish peroxidase

Question 29

The first enzyme immunoassays (EIAs) were ______ based on the principles of RIA

Answer 29

competitive assays

Question 30

This is typically used for measuring small antigens that are relatively pure

Answer 30

Heterogenous Enzyme Immunoassay

Competitive EIA

Question 31

Heterogenous Enzyme Immunoassay :Noncompetitive EIA are often referred to as _____, because the enzyme-labeled reagent does not participate in the initial antigen–antibody binding reaction

Answer 31

indirect enzyme-linked immunosorbent assays (ELISA)

Question 32

Used to detect antibodies to HIV, EBV, HBV, and HCV

Answer 32

Heterogenous Enzyme Immunoassay

Noncompetitive EIA

Question 33

Also called sandwich immunoassays

Answer 33

Heterogenous Enzyme Immunoassay

Capture Assays

Question 34

Designed primarily for point-of-care or home testing

Answer 34

Membrane-based Cassette Assays

Question 35

The membrane in Membrane-based Cassette Assays is usually ___ - able to easily immobilize proteins and nucleic acids

Answer 35

nitrocellulose

Question 36

Another type of rapid assay combines all the steps (separate addition of patient sample, wash reagent, labeled antigen or antibody, and the substrate) into one

Answer 36

immunochromatography

Question 37

It has been used to identify microorganisms (S. pyogenes and S. agalactiae), test for pregnancy, for troponin in a heart attack, and for hepatitis B surface antigen

Answer 37

Immunochromatography

Question 38

Immunochromatography Test results are most often

Answer 38

Qualitative

Question 39

Is any antigen–antibody system in which no separation step (of bound and free analyte) is necessary

Answer 39

Homogenous Enzyme Immunoassay

Question 40

Used primarily in the determination of low-molecular-weight analytes such as hormones, therapeutic drugs, and drugs of abuse in both serum and urine

Answer 40

Homogenous Enzyme Immunoassay

Question 41

Homogeneous assays are based on the principle of ______ as specific antigen–antibody combination occurs

Answer 41

change in enzyme activity

Question 42

demonstrated antibodies could be labeled molecules that fluoresce

Answer 42

Albert Coons