Question 1

Indirect immunofluorescence is similar to which type of enzyme immunoassay as far as the performance of the assay?&#10;A) competitive&#10;B) sandwich&#10;C) ELISA&#10;D) homogeneous

Accepted Answer

Indirect immunofluorescence is similar to ELISA in terms of the performance of the assay. Both assays use a labeled secondary antibody to detect the presence of the target antigen. In ELISA, the secondary antibody is conjugated to an enzyme, while in indirect immunofluorescence, the secondary antibody is conjugated to a fluorescent dye. Both assays are used for quantitative and qualitative analysis of antigens in various samples.

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

competitive EIA

Accepted Answer

In a competitive EIA, the patient antigen and labeled antigen compete for binding to a limited amount of antibody. The amount of labeled antigen measured is inversely proportional to the amount of patient antigen present.

Question 3

Components of a competitive immunoassay include all of the following EXCEPT:&#10;A) labeled analyte&#10;B) means of detection of the label&#10;C) solid-phase antibody&#10;D) standard different from the analyte

Accepted Answer

A standard different from the analyte is not a required component of a competitive immunoassay. The other components, a labeled analyte, means of detection of the label, and solid-phase antibody, are all essential for the assay to work.

Question 4

Which of the following best describes competitive binding assays?&#10;A) A limited number of binding sites are present.&#10;B) Concentration of patient antigen is directly proportional to the label detected.&#10;C) All patient antigen present is allowed to bind.&#10;D) Labeled and unlabeled analyte are present in equal amounts.

Accepted Answer

Competitive binding assays involve a limited number of binding sites, with the labeled and unlabeled analyte competing for those sites. Only a limited amount of labeled analyte can bind, resulting in a decrease in the amount of label detected as the concentration of unlabeled analyte increases.

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

Accepted Answer

This immunoassay describes the ELISA (Enzyme-linked Immunosorbent Assay) method, which uses an enzyme-labeled secondary antibody to detect the presence of specific antibodies in patient serum. The antigen is bound to a solid support and patient antibodies bind to the antigen, forming an antigen-antibody complex. The addition of enzyme-labeled anti-immunoglobulin antibodies allows for the detection of this complex, and the enzyme substrate produces a color change that can be measured to determine enzyme activity.

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:&#10;A) 2:1&#10;B) 1:2&#10;C) 3:1&#10;D) 5:1

Accepted Answer

The equation shows that there are 2 bound radioactive antigens (Ag*Ab and Ag*) and 1 bound patient antigen (AgAb), giving a ratio of 2:1.

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?&#10;A) antigen&#10;B) labeled antibody&#10;C) unlabeled antibody&#10;D) antihuman immunoglobulin

Accepted Answer

In a sandwich or capture assay, the solid phase is typically coated with an unlabeled antibody specific to the viral antigen. This antibody captures the antigen from the patient sample.

Question 8

Which of the following is characteristic of noncompetitive enzyme immunoassays?&#10;A) Binding sites for patient antigen are limited.&#10;B) Washing in between steps is not necessary.&#10;C) All patient antigen is allowed to react with binding sites.&#10;D) Color is indirectly proportional to the concentration.

Accepted Answer

In noncompetitive enzyme immunoassays, all patient antigen is allowed to react with the binding sites, ensuring that the assay measures the total amount of antigen present.

Question 9

Pregnancy testing is based on an early increase in which hormone?&#10;A) human chorionic gonadotropin&#10;B) luteinizing hormone&#10;C) thyroid-stimulating hormone&#10;D) follicle-stimulating hormone

Accepted Answer

Pregnancy testing is based on the early increase in human chorionic gonadotropin (hCG) hormone, which is produced by the placenta after a fertilized egg is implanted in the uterus. The level of hCG increases rapidly during the early weeks of pregnancy and is detectable in urine and blood samples, making it a reliable marker for pregnancy testing. Options B, C, and D are not indicative of pregnancy.

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&#10;A) 1:6&#10;B) 1:3&#10;C) 2:1&#10;D) 8:6

Accepted Answer

The equation shows that 8 radioactive antigens (ag*) and 4 patient antigens (ag) react with 6 antibodies (ab). The products include ag*ab and agab, indicating that the ratio of bound radioactive antigen (ag*ab) to bound patient antigen (agab) is 2:1.

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?&#10;A) directly proportional&#10;B) indirectly proportional

Accepted Answer

The answer of An ELISA assay was performed on a...

Question 12

In an indirect fluorescent immunoassay such as the FTA confirmatory test for syphilis,all of the following are true EXCEPT:&#10;A) A labeled antigen is used.&#10;B) Washing is an important step.&#10;C) Patient antibody is detected.&#10;D) Antihuman globulin has a fluorescent tag.

Accepted Answer

The answer of In an indirect fluorescent immunoassay such as...

Question 13

All of the following are characteristic of noncompetitive enzyme immunoassays EXCEPT:&#10;A) They are more sensitive than agglutination reactions.&#10;B) Concentration is directly proportional to the amount of color.&#10;C) Washing carefully is very important.&#10;D) Binding sites for patient antibody are limited.

Accepted Answer

The answer of All of the following are characteristic of...

Question 14

Which of the following best describes homogeneous assays?&#10;A) A washing step is necessary.&#10;B) Concentration of patient antigen is directly proportional to the label detected.&#10;C) The reagent antibody has an enzyme tag.&#10;D) Labeled and unlabeled analyte are present in equal amounts.

Accepted Answer

The answer of Which of the following best describes homogeneous...

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?&#10;A) competitive RIA using labeled antigen&#10;B) competitive EIA using labeled antigen&#10;C) noncompetitive EIA using a second labeled antibody&#10;D) any of the above

Accepted Answer

The answer of In which of the following testing situations...

Deck 10: Labeled Immunoassays