Immunohistochemistry (Wk 14, 15)

Question 1

Adding nonimmune serum to the immunoperoxidase blocking solution or antibody diluent serves to.

help attach antibodies to their target

decrease endogenous enzyme activity

decrease the effects of formalin fixation

prevent nonspecific binding of antibodies

Answer 1

prevent nonspecific binding of antibodies

Question 2

Strepatavidin-biotin-enzyme complex: strepatvidin binds what?

Answer 2

Up to 4 biotin molecules

Question 3

Antigen retrieval most likely works by?

Answer 3

Hydrolyzing methylene bridges

Question 4

A specific staining method that identifies neurofilament will detect?

Astrocytes

Microglia

Oligodendrocytes

Neurons

Answer 4

Neurons

Question 5

Suitable marker for B lymphocytes

Answer 5

L26

Question 6

Which of the following is not a suitable enzyme for labelling immunohistochemical reagents?

horseradish peroxidase

lactate dehydrogenase

alkaline phosphatase

glucose oxidase

Answer 6

Lactate dehydrogenase

Question 7

An internal control is useful because:

a) it shows that a positive is a true positive
b) it tests the sensitivity of the method
c) It tests the avidity of the method
d) It shows that a negative is a true negative

Answer 7

d) It shows that a negative is a true negative

Question 8

Addition of this mixture quenches endogenous peroxidase

Answer 8

1:1 ratio of H2O2 and methanol

Question 9

Fixation method that would LEAST affect antigen functional groups

Answer 9

Alcohol fixation

Question 10

Upon completion of an immunoperoxodase method for cytokeratin on a section of cervix, your microscopic check of the results reveal brown staining in submucosa and in surface epithelium. Your results indicate.

you have the expected staining distribution

you have non-specific background staining

the cytokeratin your section has de-localized

you are seeing crossreactivity with other intermediate filaments

Answer 10

you are seeing crossreactivity with other intermediate filaments

Question 11

2 chromogens

Answer 11

DAB - diamino benzidine

AEC - amino ethyl carbazole

Question 12

Nonspeciific background staining in immunoperoxodase staining may be prevented by?

a) increasing the antibody incubation temperature
b) increasing the ionic strength of the buffer (PBS)
c) decreasing the ionic strength of the buffer (PBS)
d) decreasing the protein concentration of the blocking solution

Answer 12

b) increasing the ionic strength of the buffer (PBS)

Question 13

Which of the following measures could be taken to help diminish background immunofluorescent staining due to hydrophobic interactions in frozen sections.

addition of detergent to the incubation buffer

increasing ionic strength of the incubation buffer

increasing the concentration of blocker protein in the incubation buffer

all of the above

Answer 13

all of the above

Question 14

Which tissue would contain the intermediate filament cytokeratin?

Simple columnar epithelium

Skeletal muscle

Cerebellum

Cartilage

Answer 14

Simple columnar epithelium

Question 15

GFAP is an immunohistochemical marker for?

Answer 15

Astrocytes

Question 16

A positive control in Immunohistochemistry should:

a) contain a large amount of the antigen of interest
b) contain a small amount of the antigen of interest
c) be the same tissue as the test slides
d) be the same kind of tumour as the test

Answer 16

b) contain a small amount of the antigen of interest

Question 17

Strong background staining in RBCs when doing IHC is most likely due to?

Answer 17

Endogenous peroxidase

Question 18

3 methods of antigen retrieval

Answer 18

• Surfactants
• Proteolytic enzymes
• Heat-mediated antigen retrieval

Question 19

Substrate when using horse radish peroxidase (HRP)

Answer 19

Hydrogen peroxide (H2O2)

Question 20

In IHC, a typical negative control would include everything except?

Answer 20

Primary antibody

Question 21

Which of the following may be used to identify neutrophils in a smear or tissue section.

a) chloroacetate esterase
b) CD3
c) surface immunoglobulin
d) metachromasia

Answer 21

a) chloroacetate esterase

Question 22

What substance is blocked from staining when avidin followed by biotin is added?

Answer 22

ENDOGENOUS biotin

Question 23

Immunoperoxidase reagent that is a suspected carcinogen

Answer 23

DAB (dry form)