Question 1

In flow cytometry, side scatter is a measure of:&#10;A) Cell size&#10;B) Protein content&#10;C) Granularity of a cell&#10;D) Expression of CD markers

Accepted Answer

In flow cytometry, side scatter is a measure of the granularity of a cell, and the forward scatter is a measure of size. The two are plotted on a graph to show different cell populations, such as lymphocytes and neutrophils.

Question 2

In flow cytometry, the side scatter and forward scatter are displayed on a graph with the purpose of:&#10;A) Identifying specific surface markers&#10;B) Separating populations of peripheral blood cells&#10;C) Determining if a specific protein is present inside a cell&#10;D) Determining if a specific signaling pathway has been activated

Accepted Answer

A graph plotting the side scatter versus the forward scatter, or granularity versus size, displays different cell populations in different areas on a graph. For example, lymphocytes will appear in a different area on the graph than neutrophils.

Question 3

In a direct immunochromatographic assay, in order for the test to be positive, a color change reaction must be evident at:
I- Test zone
II- Control zone
III- Reaction zone

A) I only
B) III only
C) I and II
D) II and III
E) I, II, and III

I and II

Accepted Answer

The urine must pass through all three areas, but a color change only occurs at the test zone if the test is positive, and then also at the control zone if the test has worked correctly.

Question 4

In an ELISA, the intensity of the color is directly proportional to:&#10;A) The antigen concentration&#10;B) The degree of drug response&#10;C) The amount of antibody added&#10;D) Nothing; the assay is not quantitative

Accepted Answer

The intensity of the color is directly proportional to the antigen concentration, so the assay is quantitative for the relative amount of an antigen in relation to a known standard quantity of the antigen.

Question 5

Which test is used to confirm a diagnosis of HIV-positive after initial testing?&#10;A) Flow cytometry&#10;B) Western blotting&#10;C) Immunochromatographic assay&#10;D) Enzyme-linked immunosorbent assay

Accepted Answer

Initial testing for HIV status is done using enzyme-linked immunosorbent assay (ELISA). However, patients who do not have HIV but are positive for other disorders, including Lyme disease and syphilis, may give a False positive ELISA for HIV. Western blotting has increased specificity for HIV and is used as a confirmation of an ELISA that indicates HIV-positive.

Question 6

When treating leukemias and lymphomas, flow cytometry can aid the physician in diagnosis and treatment by:&#10;A) Identifying increases in cell growth rates&#10;B) Identifying changes in signaling pathways&#10;C) Identifying if a drug has entered a cancer cell&#10;D) Identifying surface markers on cancerous cells

Accepted Answer

By identifying a surface marker that is specific to a certain leukemia or lymphoma, the physician can first know what disease is being treated, and secondly, can potentially choose a drug that is specific for that surface marker. For example, if a leukemic B cell is positive for the surface marker CD52, then the physician may choose to treat with alemtuzumab, which is a monoclonal antibody to CD52.

Question 7

A patient with acquired immunodeficiency syndrome (AIDS) is having lab work, and the doctor orders flow cytometry. What is flow cytometry used to detect most often in AIDS patients?&#10;A) B cell levels&#10;B) NK cell levels&#10;C) CD4 T cell levels&#10;D) CD8 T cell levels

Accepted Answer

CD4 T cells, or T helper cells, are targets for human immunodeficiency virus (HIV), and the levels can be determined by flow cytometry. Low CD4 counts indicate a high risk of infection for HIV-positive patients.

Question 8

When testing for HIV, patients can give a false positive ELISA result if the patient has which disorder?&#10;A) Rheumatoid arthritis&#10;B) Mantle cell lymphoma&#10;C) Systemic lupus erythematosus&#10;D) B cell chronic lymphocytic leukemia

Accepted Answer

Several disorders, including systemic lupus erythematosus, syphilis, Lyme disease, alcohol-related hepatitis, and hemophilia, may give a False positive for HIV with the ELISA.

Question 9

Western blots are used to identify:&#10;A) Different cell populations&#10;B) Proteins in a complex mixture&#10;C) Pregnancy hormone found in urine&#10;D) Granularity and size of a population of cells

Accepted Answer

Gel electrophoresis is used to separate out proteins by size, and then the proteins are transferred to a membrane, or Western blot, and antibodies are applied to identify a specific protein within the complex mixture of proteins in a sample.

Question 10

To identify different surface markers on a population of cells, flow cytometry requires the use of:&#10;A) Enzymes&#10;B) Colorimetric dyes&#10;C) Radioactive isotopes&#10;D) Fluorescent antibodies

Accepted Answer

The flow cytometer is able to read fluorescence, and in some cases more than one type of fluorescent signal, to determine if a fluorescently tagged antibody (or antibodies) is bound to the marker in question.

Deck 14: Antibodies and in Vitro Research and Diagnostic Assays