Question 1

Which of the following is used to standardize the procedure in flow cytometry?

Accepted Answer

Standardization in flow cytometry involves a combination of specimen handling, preparation, and gating accuracy. It is important to have a standardized procedure to ensure reliable and reproducible results. Specimen handling involves maintaining the specimen at the proper temperature and preventing it from clotting or breaking down. Specimen preparation involves proper labeling, staining, and quality control checks. Gating accuracy involves defining specific cell populations using a standardized approach, which is essential for comparing results across different samples and experiments. Therefore, all of the above factors are important for standardizing the procedure in flow cytometry.

Question 2

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

Accepted Answer

The flow chamber in a flow cytometer contains a sheath fluid and a sample fluid. These fluids are maintained at different pressures, resulting in laminar flow. The cells in the sample fluid become aligned in single file in the center of the flow chamber, allowing them to pass through the laser one-by-one for analysis.

Question 3

Which of the following is/are appropriate specimen(s) for flow cytometry?

Accepted Answer

All three choices (Blood, Bone marrow, Lymphoid tissue) are appropriate specimens for flow cytometry as they contain cells that can be analyzed using this technique. Flow cytometry can be used to analyze cell populations within these samples, including identifying and quantifying specific cell markers, studying cell cycle progression, and measuring cell viability, among other applications.

Question 4

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

Accepted Answer

The DNA index (also known as the ploidy index) is used to determine the relative DNA content of tumor cells compared to normal dividing cells. This is achieved by measuring the amount of DNA in tumor cells using flow cytometry and comparing it to a known diploid (double set of chromosomes) cell line. A DNA index of 1 indicates diploid cells, while a value greater than 1 indicates aneuploidy (abnormal number of chromosomes) which is a common feature of cancer cells. The other options (A, C, D) are used in flow cytometry to measure different aspects of cell cycle progression, but do not specifically address the relationship between tumor and normal cells.

Question 5

Which of the following is/are component(s) of a flow cytometer?

Accepted Answer

All three choices (photomultiplier tubes, sheath fluid, and flow chamber) are necessary components of a flow cytometer. Photomultiplier tubes detect the light scattered or emitted by cells passing through the flow chamber, sheath fluid helps to align the cells in a single file, and the flow chamber allows for the cells to be analyzed in a controlled stream.

Question 6

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

Accepted Answer

The answer of A single group of cells possessing identical...

Question 7

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

Accepted Answer

Flow cytometry is commonly used for immunophenotyping, which involves analyzing the types of cells present in a sample based on the markers they express.

Question 8

Choose the correct statement regarding the IRF from the choices below:

Accepted Answer

The correct statement is that the IRF is indirectly proportional to the average age of the reticulocytes. The IRF is a measure of the ratio of reticulocytes to erythrocytes in the peripheral blood and is not directly related to bone marrow turnover. It can be used to monitor erythropoietin therapy and to monitor bone marrow recovery after transplant.

Question 9

An HIV-positive patient has his blood drawn to get his CD4 count.His results are as follows: WBC count: 2.0 x 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 for the patient?

Accepted Answer

The patient's absolute CD4 count is calculated as follows:WBC count x % lymphocytes x % CD4 positive cells = Absolute CD4 count2.0 x 109/L x 15% x 10% = 300/uLAn absolute CD4 count of less than 200/uL is considered AIDS. Therefore, this patient does not have AIDS.

Question 10

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

Accepted Answer

CD5 is a marker shared by both CLL and hairy cell leukemia, but CD11c is expressed only in hairy cell leukemia, making it useful in differentially identifying the two diseases. CD19 and sIg are not specific enough to differentiate between these two types of leukemia, and CD25 is more commonly associated with other types of lymphoma.

Question 11

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

Accepted Answer

The fluorescent dye used by hematology analyzers to count reticulocytes is called thiazole orange, which binds specifically to RNA. Reticulocytes are immature red blood cells that still contain RNA, and are therefore able to be stained and counted using this dye.

Question 12

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.The dual platform uses what calculation to determine the absolute number of CD4 positive cells?

Accepted Answer

The dual platform method uses the calculation of absolute lymphocyte count multiplied by the percentage of CD4+ lymphocytes to determine the absolute number of CD4+ cells. This is because the percentage of CD4+ cells is determined by flow cytometry, and the absolute number of lymphocytes is determined separately by another method such as hematology analyzer. Therefore, the best choice is C.

Question 13

Neoplasms are made up of a population of identical cells, or a clone of cells.A clone, when identified, can lead to discovery of a lymphoid malignancy or other lymphoproliferative disorder.In what ways can clonality be detected?

Accepted Answer

Clonality in lymphoid malignancies is often detected by the uniform expression of one type of immunoglobulin light chain (either kappa or lambda), indicating a monoclonal population of cells.

Question 14

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

Accepted Answer

Lineage heterogeneity is a drawback of immunophenotyping a suspected acute leukemia because it can make it difficult to determine the lineage of the leukemia cells.

Question 15

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?

Accepted Answer

The presence of CD2 on the surface of 90% of the cells in the scatter population suggests a T cell lineage. NK cells also express CD2, but they usually have a larger and more complex scatter population. B cells and monocytes are not typically associated with CD2 expression.

Question 16

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

Accepted Answer

CD2, CD3, CD4, CD5, CD7, and CD8 are all markers commonly used in immunophenotyping for leukemia/lymphoma of T cell lineage. The presence and intensity of these markers can help determine the specific type of T cell involved in the disease. CD38, CD13, CD55, CD25, kappa, CD103, and CD61 are not as commonly used in the immunophenotyping of T cell lineage.

Question 17

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

Accepted Answer

Monoclonal antibodies have high purity and reproducibility because they are derived from a single clone of B cells, ensuring specificity for a single epitope on the antigen. In contrast, polyclonal antibodies are produced by multiple clones of B cells and can recognize multiple epitopes, leading to batch-to-batch variability in their specificity and sensitivity.

Question 18

A patient blood sample 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?

Accepted Answer

The presence of CD33 in a patient with ALL is indicative of ALL with aberrant myeloid cellular antigens. This may suggest a higher risk of relapse and poorer prognosis, as well as a potential need for tailored treatment approaches.

Question 19

Choose the accurate statement(s) regarding fluorochromes from the choices below.

Accepted Answer

All of the statements A, B, and C are accurate when it comes to fluorochromes. They absorb light of a specific wavelength and emit it at a different wavelength, which allows for their use in fluorescent microscopy and flow cytometry. They can also bind to DNA or RNA for specific labeling purposes and can be conjugated to detection antibodies for detection or quantification of specific molecules.

Question 20

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

Accepted Answer

The GPI anchor phenotype assay is the most sensitive and specific test for diagnosing PNH. It detects the absence or decrease of GPI-linked membrane proteins on red blood cells, granulocytes, and platelets. The other tests listed have lower sensitivity and specificity for PNH diagnosis.

Quiz 36: Flow Cytometry