Question 1

A single group of cells possessing identical aberrant phenotypes is defined as:
A) Monoclonal
B) Clonal
C) Tumorigenic
D) Contour gated

Accepted Answer

B

Question 2

An HIV-positive patient has his blood drawn to get his CD4 count. His results are as follows: WBC count: 2.0 × 10⁹/L with 15% lymphocytes. CD4 positive cells are 10% of the total lymphocyte count. What is this patient's absolute CD4 count, and what does this mean? A) The patient's absolute CD4 count is 300/mcL, and he has AIDS. B) The patient's absolute CD4 count is 180/mcL, and he has AIDS. C) The patient's absolute CD4 count is 300/mcL, and he does not have AIDS. D) The patient's absolute CD4 count is 120/mcL, and he does have AIDS.

Accepted Answer

The patient's absolute CD4 count is 300/mcL, and he does not have AIDS.WBC count: 2.0 × 10^9/L with 15% lymphocytes = 0.3 × 10^9 lymphocytes/LCD4 positive cells are 10% of the total lymphocyte count = 0.03 × 0.3 × 10^9 = 90/mcL

Question 3

The following are accurate statements regarding fluorochromes except which one?
A) They excite at one wavelength and emit light at a different wavelength.
B) They can bind to DNA or RNA.
C) They can be used to label detection antibodies.
D) They contribute to the scattered light caused by a cell when it travels through the flowcell.

Accepted Answer

Fluorochromes contribute to the fluorescent signal of a cell, not the scattered light caused by a cell when it travels through the flowcell. Scattered light is measured using a light scatter detector, not a fluorescence detector.

Question 4

Which of the following is used to determine the relationship between the content of tumor cells and normal dividing cells?
A) The absorbance concentration of the fluorochrome
B) The DNA index
C) The S phase fraction
D) The G2/M phase fraction

Accepted Answer

The DNA index, also known as the ploidy index, compares the amount of DNA in the tumor cells to the amount in normal dividing cells to determine their relationship. This is commonly used in flow cytometry analysis of tumor cells. The other options (A, C, and D) relate to specific phases of the cell cycle, but do not provide information about the relationship between tumor cells and normal dividing cells.

Question 5

Neoplasms are made up of a population of identical cells or a clone of cells. When identified, the clone can lead to the discovery of a lymphoid malignancy or other lymphoproliferative disorder. Clonality be detected by:
A) The uniform expression of one immunoglobulin light chain
B) A mixture of cells with either kappa or lambda light chains
C) A surface immunoglobulin detection
D) The bright intensity of all monoclonal markers

Accepted Answer

The uniform expression of one immunoglobulin light chain indicates clonality of the neoplasm. B and C are incorrect as a mixture of light chains and surface immunoglobulin detection can occur in both monoclonal and polyclonal populations. D is incorrect as the intensity of monoclonal markers can vary between different clones.

Question 6

The percentage of CD4 positive lymphocytes is determined by flow cytometry using staining with fluorescent-tagged antibodies against CD3 and CD4 followed by whole blood RBC lysis. What calculations does the dual platform use to determine the absolute number of CD4 positive cells?
A) Absolute CD4 count 100
B) Number of CD4+ cells 100
C) Absolute lymphocyte count % CD4+ lymphocytes/100
D) % lymphocytes % CD4+ lymphocytes/100

Accepted Answer

The dual platform uses the calculation of absolute lymphocyte count % CD4+ lymphocytes/100 to determine the absolute number of CD4 positive cells. This takes into account the percentage of CD4 positive lymphocytes in relation to the total lymphocyte count.

Question 7

Which of the following is considered a drawback of immunophenotyping a suspected acute leukemia?
A) AML NOC
B) Lineage heterogeneity
C) Lack of sensitivity
D) Lack of specificity

Accepted Answer

Lineage heterogeneity is a common drawback of immunophenotyping a suspected acute leukemia, as some leukemias can express markers from multiple cell lineages, leading to difficulty in accurately identifying the specific type of leukemia. AML NOC is not a recognized drawback of immunophenotyping, while lack of sensitivity and specificity can also be concerns but are not as specific to immunophenotyping.

Question 8

Which of the following is(are) the clinical application(s) of flow cytometry?
A) Assessment of total body iron
B) Immunophenotyping
C) DNA amplification
D) Cytogenetic analysis

Accepted Answer

Immunophenotyping is a primary application of flow cytometry, allowing for the analysis of cell surface and intracellular markers to identify and classify cells, particularly useful in diagnosing and monitoring hematologic malignancies.

Question 9

Of the following, which is not an appropriate specimen for flow cytometry?
A) Blood
B) Bone marrow
C) Lymphoid tissue
D) Plasma

Accepted Answer

Flow cytometry requires single-cell suspensions, and plasma does not contain cells. Therefore, it is not an appropriate specimen for flow cytometry. Blood, bone marrow, and lymphoid tissue are all appropriate specimens for flow cytometry as they all contain cells that can be analyzed using this technique.

Question 10

In diagnosing PNH, which of the following assays is most sensitive to its detection?
A) GPI anchor phenotype
B) Ham test
C) Sucrose lysis test
D) Osmotic fragility test

Accepted Answer

The GPI anchor phenotype assay is the most sensitive to the detection of PNH as it identifies the absence of GPI-linked proteins on the surface of red blood cells. This assay is considered the gold standard for PNH diagnosis. The Ham test, sucrose lysis test, and osmotic fragility test are also used in PNH diagnosis but are less sensitive and specific compared to the GPI anchor phenotype assay.

Question 11

The fluorescent dye employed by hematology analyzers to count reticulocytes binds to:
A) DNA
B) Proteins
C) RNA
D) Nucleic acids

Accepted Answer

The fluorescent dye used by hematology analyzers to count reticulocytes is called thiazole orange, which binds specifically to RNA. This allows the analyzer to distinguish immature reticulocytes (which still have RNA) from mature red blood cells (which have lost their RNA).

Question 12

Which analyte is the best indicator of the overall picture of the immune system in an HIV-positive patient?
A) Absolute CD4 count
B) Relative lymphocyte count
C) WBC count
D) Relative CD4 count

Accepted Answer

The absolute CD4 count is the best indicator of the overall picture of the immune system in an HIV-positive patient because it reflects the number of helper T cells in the body, which are the primary target of the virus. Monitoring this count can provide valuable insight into the progression of HIV and the effectiveness of antiretroviral therapy. The relative lymphocyte count and WBC count can be influenced by various factors and may not necessarily reflect the status of the immune system in the same way as CD4 counts. The relative CD4 count may be useful in certain situations, but it does not provide as clear a picture as the absolute count.

Question 13

A flow instrument printout reveals a single scatter population of small size and low complexity. Ninety percent of the cells in that population have CD2 on their surface. What is the most probable lineage of the unknown population?
A) Neutrophils
B) T cells
C) B cells
D) Monocytes

Accepted Answer

CD2 is a surface marker found on T cells, making it highly likely that the scatter population is composed of T cells. The other options are less likely to express CD2, with neutrophils having low or no expression, B cells expressing it at lower levels than T cells, and monocytes having variable expression levels.

Question 14

Which of the following is not the component(s) of a flow cytometer?
A) Photomultiplier tubes
B) Sheath fluid
C) Flow chamber
D) Hemoglobin chamber

Accepted Answer

A hemoglobin chamber is not a component of a flow cytometer. The other three components listed (photomultiplier tubes, sheath fluid, and flow chamber) are all essential parts of a flow cytometer.

Question 15

A blood sample from a patient suspected of having ALL is received in the flow lab for immunophenotyping. The analysis is performed, and standard B-cell markers are present, but the patient is also CD33-positive. What is the most likely reason for this occurrence?
A) The patient has a poorer prognosis than standard ALL.
B) The patient is responding to the chemotherapy.
C) The patient has ALL with aberrant myeloid cellular antigens.
D) It cannot be determined by the information given.

Accepted Answer

The presence of CD33 in addition to standard B-cell markers indicates the patient has ALL with aberrant myeloid cellular antigens. This may affect prognosis and treatment options.

Question 16

The flow cytometer contains a flow chamber that has two columns of fluid-sample and sheath-maintained at different pressure. Which of the following statements about the flow chamber is correct?
A) Cells in the outer column become dispersed.
B) The sample fluid has turbulent flow.
C) Cells are aligned in single file in front of the laser.
D) The two columns of fluid differ in color.

Accepted Answer

The flow chamber in a flow cytometer has two columns of fluid: sample fluid and sheath fluid. The sheath fluid is maintained at a higher pressure than the sample fluid, which causes the sample fluid to flow in a laminar (non-turbulent) stream down the center of the sheath fluid. As the sample fluid passes through the laser, cells are aligned in a single file, which allows for accurate measurement and analysis of each individual cell. The outer column of cells may become dispersed due to the laminar flow of the sample stream. The two columns of fluid may or may not differ in color, depending on the type of experiment being performed.

Question 17

Which two CD markers are helpful in differentially identifying CLL from hairy cell leukemia?
A) CD19 and CD5
B) CD5 and CD11c
C) CD5 and CD10
D) sIg and CD25

Accepted Answer

CD5 and CD11c are helpful in differentially identifying CLL from hairy cell leukemia. CLL typically expresses CD5 and weak CD11c, while hairy cell leukemia typically expresses CD11c strongly and is negative for CD5. The other options are not as specific for differentiating between CLL and hairy cell leukemia. CD19 and CD5 are commonly expressed in both CLL and hairy cell leukemia, and CD10 is typically negative in both. sIg and CD25 are not consistently expressed in either disease.

Question 18

Cells can be separated during data analysis by gating. This process of isolating cells can be based on what properties?
A) Cell size and granularity
B) Cell density
C) Shape of the nucleus
D) Color of the cytoplasm

Accepted Answer

Cells can be separated during data analysis by gating based on cell size and granularity. Cell density, shape of the nucleus, and color of the cytoplasm are not commonly used parameters for gating.

Question 19

Which markers are useful in immunophenotyping for leukemia/lymphoma of T cell-lineage?
A) CD103, CD61, and CD59
B) CD38, CD59, and CD13
C) CD2, CD3, CD4, CD5, CD7, and CD8
D) CD55, CD25, and kappa

Accepted Answer

CD2, CD3, CD4, CD5, CD7, and CD8 are all markers commonly used in immunophenotyping for leukemia and lymphoma of T cell-lineage. Utilizing these markers helps identify the specific type of T cell present and aids in making a diagnosis and determining the appropriate treatment plan. The other markers listed (CD103, CD61, CD59, CD38, CD13, CD55, and kappa) are not typically used in T cell immunophenotyping.

Question 20

What is one advantage to using monoclonal antibodies rather than polyclonal antibodies in immunophenotyping?
A) They are commercially available.
B) The antigen can be recognized even if some parts of it are abnormal.
C) They have high purity and reproducibility.
D) They can be directly attached to fluorochromes.

Accepted Answer

Monoclonal antibodies have high purity and reproducibility because they are produced by identical immune cells that are clones of a single parent cell, which ensures that each antibody recognizes the same epitope. On the other hand, polyclonal antibodies are produced by multiple immune cells that recognize different epitopes on the antigen, leading to batch-to-batch variabilities and inconsistent results. This makes monoclonal antibodies a better choice for immunophenotyping, which requires reliable and consistent detection of specific surface markers on cells.

Quiz 40: Flow Cytometry

A single group of cells possessing identical aberrant phenotypes is defined as:

An HIV-positive patient has his blood drawn to get his CD4 count. His results are as follows: WBC count: 2.0 × 109/L with 15% lymphocytes. CD4 positive cells are 10% of the total lymphocyte count. What is this patient's absolute CD4 count, and what does this mean?

The following are accurate statements regarding fluorochromes except which one?

Which of the following is used to determine the relationship between the content of tumor cells and normal dividing cells?

Neoplasms are made up of a population of identical cells or a clone of cells. When identified, the clone can lead to the discovery of a lymphoid malignancy or other lymphoproliferative disorder. Clonality be detected by:

The percentage of CD4 positive lymphocytes is determined by flow cytometry using staining with fluorescent-tagged antibodies against CD3 and CD4 followed by whole blood RBC lysis. What calculations does the dual platform use to determine the absolute number of CD4 positive cells?

Which of the following is considered a drawback of immunophenotyping a suspected acute leukemia?

Which of the following is(are) the clinical application(s) of flow cytometry?

Of the following, which is not an appropriate specimen for flow cytometry?

In diagnosing PNH, which of the following assays is most sensitive to its detection?

The fluorescent dye employed by hematology analyzers to count reticulocytes binds to:

Which analyte is the best indicator of the overall picture of the immune system in an HIV-positive patient?

A flow instrument printout reveals a single scatter population of small size and low complexity. Ninety percent of the cells in that population have CD2 on their surface. What is the most probable lineage of the unknown population?

Which of the following is not the component(s) of a flow cytometer?

A blood sample from a patient suspected of having ALL is received in the flow lab for immunophenotyping. The analysis is performed, and standard B-cell markers are present, but the patient is also CD33-positive. What is the most likely reason for this occurrence?

The flow cytometer contains a flow chamber that has two columns of fluid-sample and sheath-maintained at different pressure. Which of the following statements about the flow chamber is correct?

Which two CD markers are helpful in differentially identifying CLL from hairy cell leukemia?

Cells can be separated during data analysis by gating. This process of isolating cells can be based on what properties?

Which markers are useful in immunophenotyping for leukemia/lymphoma of T cell-lineage?

What is one advantage to using monoclonal antibodies rather than polyclonal antibodies in immunophenotyping?

An HIV-positive patient has his blood drawn to get his CD4 count. His results are as follows: WBC count: 2.0 × 10⁹/L with 15% lymphocytes. CD4 positive cells are 10% of the total lymphocyte count. What is this patient's absolute CD4 count, and what does this mean?