Deck 11: Clinical Applications of Flow Cytometry

Question 1

How many fluorochromes can the average flow cytometer detect?

A)2-4
B)1 at a time
C)6-8
D)>10

Answer 1

2-4

Question 2

What is the usual light source for a flow cytometer?

A)Ultraviolet lamp
B)Deuterium lamp
C)Tungsten lamp
D)Laser

Answer 2

Laser

Question 3

Flow cytometry can be used to determine the presence of fetal cells in a blood specimen by using

A)monoclonal antibody to hemoglobin A1.
B)alkaline elution.
C)monoclonal antibody to hemoglobin F.
D)acid elution.

Answer 3

monoclonal antibody to hemoglobin F.

Question 4

A flow cytometry analysis was set up as follows. How can T helper cells be identified? Analysis of forward and side laser light scatter anti- CD3 labeled with green fluorochrome anti- CD4 labeled with red fluorochrome
Anti- CD8 labeled with yellow fluorochrome anti- CD19 labeled with blue fluorochrome

A)Select cells with the highest forward and lowest side scatter plus red and green fluorescence.
B)Select cells with the lowest forward and highest side scatter plus red fluorescence only.
C)Select cells with the lowest forward and side scatter plus yellow and green fluorescence.
D)Select cells with the lowest forward and side scatter plus red and blue fluorescence.
E)Select cells with the lowest forward and side scatter plus red and green fluorescence.

Question 5

A transplant recipient showed signs of rejection, so she was treated with monoclonal anti- CD3 (OKT3). Flow cytometry was done on her blood after treatment with results as shown in the figure. The gate was set on lymphocytes. What is the best interpretation of that analysis given?

A)The treatment is working adequately.
B)The treatment is not working adequately.
C)The fluorescent compensation was not set correctly.
D)The lymphocyte gate was not set correctly.

Question 6

Which of the following cells should scatter the most light in the side angle?

A)Monocyte
B)Red blood cell
C)Lymphocyte
D)Neutrophil

Question 7

In a flow cytometer, the amount of light scattered by a cell at a 90° angle (side scatter)is detected by a .

A)photomultiplier tube.
B)tungsten lamp.
C)phototube.
D)photodiode.
E)laser.

Question 8

In AIDS patients, when the CD4+ lymphocyte count falls, the patient is more vulnerable to

A)opportunistic bacterial infections.
B)opportunistic fungal infections.
C)malignancies.
D)opportunistic viral infections.
E)All of the above.

Question 9

Which of the cells below should scatter the most light in the forward angle?

A)Monocyte
B)Basophil
C)Neutrophil
D)Lymphocyte
E)Eosinophil

Question 10

When staining cells for flow cytometry, which technique would have the least amount of nonspecific staining?

A)Monoclonal antibody, indirect staining
B)Monoclonal antibody, direct staining
C)Polyclonal antibody, direct staining
D)Polyclonal antibody, indirect staining

Question 11

Each of the following is a step in screening organ recipient serum for HLA antibodies except

A)Step 1: A panel of latex beads is coated with HLA antigens.
B)Step 2: Recipient serum is mixed with each HLA antigen.
C)Step 5: The latex beads are put in the flow cytometer and analyzed for agglutination based on increased forward scatter of agglutinated particles.
D)Step 4: Fluorochrome- labeled antihuman globulin is mixed with the latex beads.
E)Step 3: After serum has incubated with the beads, they are washed to remove all excess serum.

Question 12

Which of the following is(are)essential characteristics of the fluidic system of a flow cytometer?

A)Adjust the rate of diluent flow depending on cell count (i.e., slower flow for specimens with high counts).
B)Create a hydrodynamically focused sheath fluid that will cause the cells to flow past the laser in single file.
C)Maintain a slow moving, low pressure solution flow such that there is sufficient time to analyze each cell.
D)All of the above.

Question 13

Why are whole blood, bone marrow, and bronchoalveolar lavage specimens typically good specimens for flow cytometry?

A)The sizes of cells in these specimens fall within the range that can be analyzed by laser light scatter.
B)There is less debris in these specimens to non- specifically scatter light.
C)The cell types in these specimens usually have more well- defined antigens.
D)These are generally cell suspensions with cells occurring separately and singly in the mixture.

Question 14

How are cell surface antigens detected by a flow cytometer?

A)Light scatter in the side angle
B)Light scatter in the forward angle
C)Radioactivity of isotopes on attached monoclonal antibodies
D)Absorbance of chromogens on attached monoclonal antibodies
E)Fluorescence of fluorochromes attached monoclonal antibodies

Question 15

All of the following are TRUE regarding specimen handling for flow cytometry except

A)ammonium chloride is used to lyse granulocytes when mononuclear cells need to be analyzed.
B)tissues must be homogenized into single cell suspensions.
C)a minimum number of cells must be present for analysis to be accurate.
D)specimens must be processed promptly to insure cell viability.
E)cell surface antigens must be stabilized with paraformaldehyde.

Question 16

When a patient is HIV positive and the CD4+ lymphocyte count falls below 200/ uL, what does this mean?

A)The patient is extremely vulnerable to opportunistic infections.
B)The patient meets the CD4 count diagnostic criterion for AIDS.
C)Prophylactic antibiotics should be started.
D)All of the above.

Question 17

In the scatterplot shown, in which population would eosinophils be found?

A)A
B)B
C)C
D)None of the above

Question 18

It is desirable before a transplant that the donor cells be cross- matched with the recipient's serum to rule out preexisting antibodies in the recipient. What advantage is there in doing the cross- match by flow cytometry?

A)The equipment is less expensive.
B)Flow cytometry is more sensitive that other techniques.
C)Donor cells do not have to be viable.
D)Flow cytometry is more specific that other techniques.

Question 19

What characteristic(s)of a cell can be determined by a flow cytometer?

A)Internal complexity
B)Cell surface antigens
C)Size
D)All of the above

Question 20

A flow cytometry analysis was done and the gate was set on the lymphocytes. Observe the analysis below of the cells in the gate possessing the CD4 and CD3 markers. In which quadrant are T helper cells found?

A)Quadrant A
B)Quadrant B
C)Quadrant C
D)Quadrant D
E)Quadrants B and D

Question 21

Which of the following changes are possible in malignant cells?

A)Antigen from a different cell lineage is expressed.
B)Expected antigen is missing.
C)Antigen from a different stage of development is expressed.
D)All of the above.

Question 22

A patient presented with a very high white blood count with 90% lymphocytes. Flow cytometry analysis was done with the gate set on the lymphocytes. What is the best interpretation of the results below?

A)B cell leukemia
B)Granulocytic leukemia
C)T cell leukemia
D)Leukocytosis due to infection

Question 23

Flow cytometry can be done to identify small malignant cell populations within a normal larger population. It is therefore especially important that specimens are

A)handled as promptly as possible.
B)examined for cell viability.
C)preserved if analysis is delayed.
D)All of the above.

Question 24

Reticulocytes can be analyzed using flow cytometry when they are stained with ethidium bromide.

Question 25

When stem cell harvests are done for hematopoietic progenitors, flow cytometry is done for the marker as it is highly associated with elevated levels of progenitor cells.

Question 26

Serial measurements of positive lymphocytes in HIV patients are done by flow cytometry to determine when prophylactic antibiotics should be given.

Question 27

When antiretroviral therapy is successful in AIDS patients, the count of CD4+ lymphocytes will increase.

Question 28

In order for flow cytometry analysis to work properly, the cells must be dead in order to properly take up stain.

Question 29

Effective antibody reagents in flow cytometry are produced by hybridoma cells and are
.

Question 30

When different flourochromes are used in flow cytometry that have overlapping emission spectra, the interference can be electronically subtracted using a process called fluorescence
.

Question 31

When patients are put on the waiting list for a kidney transplant, they are tested for alloantibodies to HLA antigens when they are initially put on the list and then a second time just prior to the transplant.

Question 32

Fluorochromes absorb light at one wavelength and then emit light at a shorter wavelength.

Question 33

Labeled monoclonal antifetal hemoglobin can be mixed with fixed red blood cells to detect fetal red cells.

Question 34

A specimen has a total white blood count of 10,000 cells/uL of which 35% are lymphocytes. Flow cytometry analysis revealed that 50% of the lymphocytes are CD4+, so the absolute CD4 count is cells/uL.

Question 35

In flow cytometry, the process by which the cell population to be analyzed is selected is called fluorescence compensation.

Question 36

Using flow cytometry, cell markers can be detected that will determine a cell's

A)lineage.
B)surface marker expression.
C)maturational stage.
D)All of the above.

Question 37

A flow cytometry analysis was done as shown in the figure with the gate set on red blood cells. What is the most likely interpretation of the analysis?

A)The red cells were all lysed in the preparation.
B)The gate is contaminated with white blood cells.
C)The patient may have a glucose- 6- phosphate dehydrogenase deficiency.
D)The patient may have paroxysmal nocturnal hemoglobinuria.
E)The reticulocyte population is elevated.

Question 38

Although all human white cells possess the CD45 marker, immature cells possess less of it and stain dimly on flow cytometry analysis.

Question 39

Once cells have been fixed in paraformaldehyde for flow cytometry analysis, they must be analyzed immediately or the cell surface markers will deteriorate.

Question 40

Cell analysis in flow cytometry can be done using fluorescent stains for nucleic acids such as DNA.

Question 41

Describe both direct and indirect antigen staining in flow cytometry and the advantages and disadvantages of each.

Question 42

Describe how data are collected and displayed in flow cytometry.

Question 43

Explain how flow cytometry and hematology cell counting are both used to obtain absolute CD4+ lymphocyte counts.

Question 44

How is flow cytometry used to determine if a donor bone marrow aspirate or stem cell harvest is adequate to repopulate a bone marrow?

Question 45

Explain why determining the amount of fetal bleed into a mother is essential for preventing hemolytic disease of the newborn.