Deck 10: Labeled Immunoassays

Question 1

Indirect immunofluorescence is similar to which type of enzyme immunoassay as far as the performance of the assay?

A) competitive
B) sandwich
C) ELISA
D) homogeneous

Answer 1

ELISA

Question 2

An immunoassay is performed in the following manner to look for an Ag in the patient serum: Patient serum + labeled Ag + known Ab are added together and incubated.Unbound material is washed off.The amount of labeled Ag is then measured.What assay is performed?

A) homogeneous EIA
B) competitive EIA
C) sandwich EIA
D) ELISA

Answer 2

competitive EIA

Question 3

Components of a competitive immunoassay include all of the following EXCEPT:

A) labeled analyte
B) means of detection of the label
C) solid-phase antibody
D) standard different from the analyte

Answer 3

standard different from the analyte

Question 4

Which of the following best describes competitive binding assays?

A) A limited number of binding sites are present.
B) Concentration of patient antigen is directly proportional to the label detected.
C) All patient antigen present is allowed to bind.
D) Labeled and unlabeled analyte are present in equal amounts.

Question 5

An immunoassay was performed in the following way: Antigen is bound to a solid support.Patient serum is added and patient antibodies bind to the antigen.The well is washed and enzyme-labeled anti-immunoglobulin antibodies are added.The well is washed and enzyme substrate is added and enzyme activity is determined.Which immunoassay is described?

A) sandwich
B) competitive
C) ELISA
D) homogeneous

Question 6

In the following equation,10 Ag* + 5 Ag + 3 Ab ---> Ag*Ab + Ag Ab + Ag* + Ag,the ratio of bound radioactive antigen to bound patient antigen is:

A) 2:1
B) 1:2
C) 3:1
D) 5:1

Question 7

In a sandwich or capture assay to determine the presence of a viral antigen in a patient sample,which of the following would be on solid phase?

A) antigen
B) labeled antibody
C) unlabeled antibody
D) antihuman immunoglobulin

Question 8

Which of the following is characteristic of noncompetitive enzyme immunoassays?

A) Binding sites for patient antigen are limited.
B) Washing in between steps is not necessary.
C) All patient antigen is allowed to react with binding sites.
D) Color is indirectly proportional to the concentration.

Question 9

Pregnancy testing is based on an early increase in which hormone?

A) human chorionic gonadotropin
B) luteinizing hormone
C) thyroid-stimulating hormone
D) follicle-stimulating hormone

Question 10

In the following equation,what is the ratio of bound radioactive antigen to bound patient antigen? 8ag* + 4ag + 6ab ---> ag*ab + agab + ag* + ag

A) 1:6
B) 1:3
C) 2:1
D) 8:6

Question 11

An ELISA assay was performed on a patient's serum sample.What is the relationship of the amount of enzyme activity to the amount of patient analyte measured?

A) directly proportional
B) indirectly proportional

Question 12

In an indirect fluorescent immunoassay such as the FTA confirmatory test for syphilis,all of the following are true EXCEPT:

A) A labeled antigen is used.
B) Washing is an important step.
C) Patient antibody is detected.
D) Antihuman globulin has a fluorescent tag.

Question 13

All of the following are characteristic of noncompetitive enzyme immunoassays EXCEPT:

A) They are more sensitive than agglutination reactions.
B) Concentration is directly proportional to the amount of color.
C) Washing carefully is very important.
D) Binding sites for patient antibody are limited.

Question 14

Which of the following best describes homogeneous assays?

A) A washing step is necessary.
B) Concentration of patient antigen is directly proportional to the label detected.
C) The reagent antibody has an enzyme tag.
D) Labeled and unlabeled analyte are present in equal amounts.

Question 15

In which of the following testing situations is there a direct relationship between the amount of bound label and the amount of patient antigen present?

A) competitive RIA using labeled antigen
B) competitive EIA using labeled antigen
C) noncompetitive EIA using a second labeled antibody
D) any of the above