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flow cytometry
Question | Answer |
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__________ is an automated system in which single cells in a fluid suspension are analyzed in terms of their intrinsic light-scattering characteristics. | Flow cytometry |
The cells are also simultaneously evaluated for extrinsic properties (usually specific surface proteins) using ________ | fluorescent-labeled antibodies or probes |
Flow cytometers can simultaneously measure ___________. | multiple cellular properties |
Because the flow rate of cells within the cytometer is so rapid, thousands of cells can be analyzed in seconds, allowing for the accurate detection of ___________. | very rare cells |
The major __________include the fluidics, the laser light source, the optics and photodetectors, and a computer for data analysis and management. | components of a flow cytometer |
Cells are processed into a ________, and the cytometer draws up the cell suspension and injects the sample inside a carrier stream of __________ (sheath fluid) to form a laminar flow. | suspension; isotonic saline |
The sample stream is constrained by the carrier stream and is thus __________ focused so that the cells pass in a single file through the intersection of the laser light source | hydrodynamically focused |
Each cell is interrogated by a _______ that typically consists of one or more small air-cooled _________. | light source; lasers |
Cells are labeled with a_________, or fluorescent molecule, that absorbs light across a spectrum of wavelengths and emits light of lower energy across a spectrum of longer wavelengths. | fluorochrome |
Each fluorochrome has a distinctive spectral pattern of __________ | absorption (excitation) and emission. |
The choice of fluorochromes to be used in an assay depends on the light source used for _____. | excitation |
Many flow cytometers utilize a second laser to increase flexibility in _________ selection | fluorochrome |
Light at two specific angles is measured by the __________: forward-angle light scatter (FSC), and orthogonal right angle light scatter, or 90-degree-angle light scatter (SSC). | flow cytometer |
________, or light scattered at less than 90 degrees, is considered an indicator of cell size, while the _______ signal is indicative of granularity or intracellular complexity of the cell. | FSC; SSC |
FSC, or light scattered at less than 90 degrees, is considered an indicator of _______ | cell size |
the SSC signal is indicative of __________of the cell. | granularity or intracellular complexity |
FSC and SSC are considered _____, can be used to characterize different cell types. | intrinsic parameters |
In a sample of whole blood, the three major populations of white blood cells (___________) can be roughly differentiated from each other based solely on their _________ | lymphocytes, monocytes, and granulocytes; intrinsic parameters |
Extrinsic parameters of cells require the addition of a ________ for their detection. | fluorescent probe |
___________ antibodies bound to the cell are interrogated by the laser or lasers of the ________concurrently with measurements of the cell’s FSC and SSC. | Fluorescent labeled; cytometer |
FSC, SSC, and fluorescence signals generated by the cells’ interaction with the laser are detected by photomultiplier tubes and detectors within the __________ | optic system |
Once the intrinsic and extrinsic cellular properties of many cells have been collected and the data digitalized by the data __________, the data set is ready for analysis by the operator. | data analysis and management system |
Typically, 10,000–20,000 “events” are collected for ______ sample. | each |
The first level of data representation is the _________, which plots a chosen parameter (generally fluorescence) on the x-axis versus the number of events on the y-axis | single-parameter histogram |
The next level of representation is the ___________, or dual-parameter dot plot, where each dot represents an individual cell or event. | bivariant histogram |
The operator chooses which parameters to analyze on both the x- and y-axes and then divides the dot plot into _________, separating the positives from the negatives in each axis. | four quadrants |
For example, the lymphocytes can be gated, and then the subpopulations of T cells ( _____) and B cells ( ___)can be analyzed | CD3+ and CD4+ or CD2+; CD2- CD19+ |
Detailed phenotypic analysis can determine the __________, as well as the degree of differentiation and activation, of a cell population. | lineage and clonality |
Samples commonly used for analysis in Flow cytometry include ________. | whole blood, bone marrow, and fluid aspirates |
Blood should be stored at _______ (20ºC–25ºC) prior to processing and should be ________ before being pipetted into staining tubes. | room temperature; well mixed |
_______ or clotted specimens should be rejected. | Hemolyzed |
Samples with large numbers of red cells require ________ removal to allow for efficient analysis of _________. | erythrocyte; white cells |
Historically, _______ with Ficoll-Hypaque was used to generate a cell suspension enriched for lymphocytes or blasts | density gradient centrifugation |
density gradient centrifugation was used to generate a ________, enriched for lymphocytes or ____. | cell suspension; blasts |
Ficoll-Hypaque - However this method results in selective ______ of some cell populations. | loss |
Routine applications of _______in the clinical laboratory include ____ of peripheral blood lymphocytes, enumeration of ___ cells in peripheral blood and bone marrow for use in stem cell transplantation. | flow cytometry; immunophenotyping; CD34+ stem |
________ is a characterization of acute leukemias, non-Hodgkin’s lymphomas, and other lymphoproliferative disorders. | immunophenotypic |
Immunophenotyping by flow cytometry has become an important component of initial evaluation and subsequent post-therapeutic monitoring in _________ | leukemia and lymphoma management. |
Enumeration of peripheral blood CD4+ T cells in HIV-infected patients remains the highest volume test performed in the flow cytometry laboratory, because it is used in classifying ________ and determining treatment options. | stages of HIV disease |
Additional examples of applications of flow cytometry include the determination of DNA content, or _______, of tumor cells | ploidy status |
Monitoring patients who have been treated for leukemia or lymphoma for “_________disease” | minimal residual |
In the case of a _____hemorrhage, flow cytometry is much more sensitive than the traditional Kleihauer-Betke method to detect __________ positive cells. | fetal–maternal hemorrhage; hemoglobin F |
Flow cytometry is also being used in ______________ (HLA) typing and cross-matching for solid organ transplantation | human leukocyte antigen |
There are currently two main types of immunoassay analyzers on the market:_____ analyzers and _________ analyzers | batch ; random access |
_____ analyzers can examine multiple samples and provide access to the test samples for the formation of _________ reaction mixtures. | Batch analyzers; subsequent |
________ analyzers, in which multiple test samples can be analyzed and multiple testing can be performed on any test sample, can allow stat samples to be loaded ________ and multiple analyses on any one sample | Random access; randomly |
Automation can and does occur in all three stages of laboratory testing: ___ _________ _______ stages. | the preanalytical, analytical, and postanalytical stages. |
Regardless of the instrumentation considered, proper validation of _________ must always be performed | new instrumentation or methodology |
The laboratory must determine how it will meet __________ regulations for verifying the manufacturer’s performance specifications and information regarding method/instrument validation. | Clinical Laboratory Improvement Amendment (CLIA) |
As designated by CLIA, the required verifications to be determined for a new method are accuracy, precision,______ , _________, interfering substances, reportable range, and reference intervals. | analytic sensitivity, analytic specificity |