Immunohistochemistry

Question 1

An antigen is a substance that triggers the production of:

Answer 1

immunoglobins

Question 2

A light chain present in some antibodies is:

Answer 2

kappa

Question 3

Different molecular sites on antigens are known as:

Answer 3

epitopes

Question 4

When an antibody labeled with a chromogen is reacted with tissue from a patient, the IHC technique is called:

Answer 4

direct

Question 5

Which of the following is a fluorochrome:

a. alkaline phosphatase
b. rhodamine
c. fast red
d. diamineobenzidine

Answer 5

rhodamine

Question 6

In the indirect IHC method the…

Answer 6

patients serum is added to tissue sections containing known antigens

Question 7

In the avidin-biotin methods, the primary antibody is followed by:

Answer 7

biotinylated secondary antibody

Question 8

A dye that absorbs light and then emits its own light at a longer wavelength is known as:

Answer 8

a fluorochrome

Question 9

In some IHC tehcniques, alkaline phosphatase functions as the:

Answer 9

enzyme

Question 10

Horseradish peroxidase is used in some avidin-biotin methods as the:

Answer 10

enzyme

Question 11

A substrate for alkaline phosphatase-labeled antibodies is commonly:

Answer 11

napthol-AS-phosphate

Question 12

Which of the following chromogens is INSOLUBLE in alcohol:

a. fast red TR
b. 3,3’-diaminobenzidine tetrahydrochloride (DAB)
c. 3-amino-9-ethylcarbazole (AEC)
d. fast blue BBN

Answer 12

b. 3,3’-diaminobenzidine tetrahydrochloride (DAB)

Question 13

IF 3-amino-9-ethylcarbazole is used as a chromagen, the hematoxylin used for counterstaining should be:

Answer 13

alcohol free

Question 14

Tissue for immunoflourescence must be:

Answer 14

frozen and unfixed

Question 15

A neoplasm is defined as a/an:

Answer 15

new growth of uncontrolled cell multiplication

Question 16

What is NOT a proper approach to validation of a new antibody?

Answer 16

using only the manufacturers recommendations

Question 17

When the vimentin stain is completely negative on formalin-fixed tissues, this indicates that most likely the tissue has been:

Answer 17

overfixed

Question 18

Besides the heat employed, another important factor in head-induced epitope retrieval (HIER) us the:

Answer 18

composition of the solution used

Question 19

Ficin is used in IHC for:

Answer 19

enzyme-induced epitope enhancement

Question 20

What has been eliminated with polymeric IHC staining methods?

Answer 20

serum and avidin-biotin blocking steps

Question 21

In the peroxidase-antiperoxidase (PAP) method of antigen detection, the PAP complex is made in the same species as:

Answer 21

the primary antibody

Question 22

Imidazole may be used in peroxidase techniques to:

Answer 22

intensify the DAB reaction

Question 23

What link antibodies would most likely follow as a monoclonal primary antibody?

Answer 23

rabbit anti-mouse

Question 24

T/F: Prediluted antibodies should always be used as provided by the mansufacturer.

Answer 24

False.

Question 25

T/F: Negative tissue antigen controls may be run by substituting for the primary antibody the diluent in which the antibody is prepared.

Answer 25

True

Question 26

T/F: One standard staining protocol may be written to cover all specimens.

Answer 26

False.

Question 27

T/F: Zinc formalin preserves immunoreactivity well.

Answer 27

True.

Question 28

T/F: Multilink antibodies can be used only with monoclonal primary antibodies.

Answer 28

False.

Question 29

T/F: Blocking reactions are used to block endogenous activity of the same enzyme as that used for the enzyme immune complex.

Answer 29

True

Question 30

T/F: The enzyme label for immunoperoxidase methods contain horseradish peroxidase.

Answer 30

True

Question 31

T/F: Monoclonal antibodies are often preferred over polyclonal antibodies because there is no batch-to-batch variability.

Answer 31

True.

Question 32

T/F: DAB is an alcohol-soluble chromagen.

Answer 32

False.

Question 33

T/F: Harris hematoxylin should not be used with 3-amino-9-ethylcarbazole (AEC) because of the alcohol present.

Answer 33

True.

Question 34

T/F: Regulation regarding predictive marker staining of the tissue places responsibility for documenting time in the fixative on the laboratory.

Answer 34

True.

Question 35

T/F: The only method of heat-induced epitope retrieval involves using a microwave oven.

Answer 35

False.

Question 36

T/F: Optimal dilutions for each antibody must be determined by your lab.

Answer 36

true

Question 37

T/F: Metal salts involving nickel, copper, and osmium may be used to intensify 3-amino-9-ethylcarbazole reaction.

Answer 37

False. Metal salts intensift DAB.

Question 38

T/F: Alkaline phosphatase label can be substituted for peroxidase label in most IHC methods.

Answer 38

True

Question 39

T/F: Precut control slides may be stored at room temp indefinitly.

Answer 39

False.

Question 40

In the bloody areas of a tissue section stain with the immunoperoxidase technique, there is a marked reaction of the red blood cells. This is most likely the result of:

Answer 40

failure to use hydrogen peroxide. It is essential to reduce non-specific staining of RBCs.

Question 41

Paraffin sections stained with the immunoperoxidase technique show excess background staining. What could explain this?

Answer 41

Forgetting to apply the non-immune serum. If the first protein solution applied to the tissue is the primary antibody, nonspecific binding can occur.

Question 42

The skin control for S-100 was stained with the immunoalkaline phosphatase technique using fast red TR as the chromogen. It shows negative staining. One possible explanation is:

Answer 42

sections were dehydrated and cleared. With prolonged dehydration, the alkaline phosphatase chromogen can break down.

Question 43

At the end of the immunoperoxidase staining procedure, it was realized that an anti-goat linking antibody was used with monoclonal HMB-45 antibody. Microscopic results should show a:

Answer 43

negativity stained positive control and a negative stained specimen since monoclonal antibodies are most often prepared by mice or rabbits. An anti-mouse, anti-rabbit or multilink linking secondary must be used.

Question 44

Both the known positive control and the specimen are negative following immunoperoxidase staining with LCA primary antibody. DAB was used as a chromogen. What could be the cause?

Answer 44

wrong secondary antibody was used. The secondary antibody must be targeted to the primary for linking to occur.

Question 45

Excessive background is noted on both the control and specimen stained with immunoperoxidase. This might be due to:

Answer 45

insufficient washing with buffer

Question 46

Excessive background is noted on the specimen but not the control stained with immunoperoxidase. This is most likely due to:

Answer 46

free antigen in the tissue

Question 47

Both the positive control and the specimen stained with immunoalkaline phosphatase using CEA antibody show very weak staining. Why?

Answer 47

incorrectly diluted antibody.