Labeled Immunoassays Textbook Questions Flashcards
Which of the following statements accurately describes heterogeneous competitive binding immunoassays?
a. Excess binding sites for the analyte are provided.
b. Test signal is generated in solution without the need of a solid-phase support material.
c. The concentration of patient analyte is inversely proportional to bound label.
d. All the patient analyte is bound in the reaction.
c. The concentration of patient analyte is inversely proportional to bound label.
How do heterogeneous immunoassays differ from homogeneous immunoassays?
a. Heterogeneous immunoassays require a separation step.
b. Heterogeneous immunoassays require less technical skill to perform than homogeneous immunoassays.
c. For noncompetitive immunoassays, the concentration of patient analyte is indirectly proportional to bound label in heterogeneous immunoassays.
d. Homogeneous immunoassays have better analytical sensitivity compared with heterogeneous immunoassays.
a. Heterogeneous immunoassays require a separation step.
Which of the following responses characterizes a capture or sandwich enzyme immunoassay?
a. Less analytically sensitive than competitive enzyme immunoassays
b. Labeled antigen attached to a solid phase
c. Best for small antigens with a single epitope determinant
d. Excess number of antibody sites on solid-phase material
d. Excess number of antibody sites on solid-phase material
Which of the following is an advantage of enzyme immunoassay over radioimmunoassay?
a. Decrease in hazardous waste
b. Shorter shelf life of kit reagents
c. No interference by biological inhibitors
d. Must be read manually
a. Decrease in hazardous waste
Which of the following is characteristic of direct fluorescence immunoassays?
a. The anti-immunoglobulin has the fluorescent tag.
b. Antibody is attached to a solid phase.
c. This method can be used for rapid identification of microbial antigens.
d. The amount of color is inversely proportional to the amount of antigen present.
c. This method can be used for rapid identification of microbial antigens.
Which of the following is true of the enzyme-multiplied immunoassay technique (EMIT)?
a. It is classified as a heterogeneous method.
b. Nicotinamide adenine dinucleotide (NAD+) is a substrate used in the test reaction.
c. When the patient sample antigen concentration is high, the final test signal will be low.
d. Patient sample antigen blocks the enzyme active site in the test reaction.
b. Nicotinamide adenine dinucleotide (NAD+) is a substrate used in the test reaction.
A fluorescent substance is best described as one in which
a. light energy is absorbed and converted to a longer wavelength.
b. the emitted wavelength can be seen under normal white light.
c. there is a long time between the absorption and emission of light.
d. it spontaneously decays and emits light.
a. light energy is absorbed and converted to a longer wavelength.
In a noncompetitive ELISA, if a negative control shows the presence of signal, which of the following might be a possible explanation?
a. No reagent was added.
b. Washing steps were incomplete.
c. The enzyme was inactivated.
d. No substrate was present.
b. Washing steps were incomplete.
Which of the following best characterizes chemiluminescent immunoassays?
a. Only the antigen can be labeled.
b. Tests can be read manually.
c. These are only homogeneous immunoassays.
d. A chemical is oxidized to produce light.
d. A chemical is oxidized to produce light.
Immunofluorescence assays may be difficult to interpret for which reason?
a. Autofluorescence of substances in serum
b. Nonspecific binding to serum proteins
c. Subjectivity in reading results
d. Any of the above
d. Any of the above
Which statement best describes rapid immunochromatographic assays?
a. Test results are always reported as quantitative values.
b. They are designed primarily for point-of-care testing.
c. Urine is the only acceptable sample type.
d. Formation of a colored line always indicates a positive result.
b. They are designed primarily for point-of-care testing.
Which of the following is characteristic of an indirect enzyme immunoassay?
a. The first antibody has the enzyme label.
b. Only one antibody is required.
c. Color is directly proportional to the amount of patient antibody present.
d. Enzyme specificity is not essential.
c. Color is directly proportional to the amount of patient antibody present.
In an indirect ELISA, what would be the outcome of an improper wash after the antibody–enzyme conjugate is added?
a. Results will be falsely decreased.
b. Results will be falsely increased.
c. Results will be unaffected.
d. No wash step is required in the ELISA procedure.
b. Results will be falsely increased.
In a heterogeneous enzyme immunoassay, if the patient sample produces more signal than the highest positive control, what action should be taken?
a. Report the results out as determined.
b. Dilute the patient sample.
c. Repeat the immunoassay using one-half the volume of the patient sample.
d. Report the results as falsely positive.
b. Dilute the patient sample.
Which of the following can uniquely cause interferences in immunoassays designed with streptavidin bound to the solid-phase surface?
a. Elevated concentration of biotin in the patient test sample can cause falsely increased results.
b. Heterophile antibodies present in the patient sample cause falsely decreased results.
c. Antibody excess in the patient sample leads to a hook effect.
d. Solid-phase particles will dissolve easily if the reaction temperature is increased.
a. Elevated concentration of biotin in the patient test sample can cause falsely increased results.
