Automated Cell Counters
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Automated Cell Counters
What are the advantages of automated cell counters over manual cell counting?
More accurate results (many more cells are counted)
Relatively simple to operate
Perform multiple tests
What are the disadvantages of automated cell counters?
Multiple sources of error (if you don't keep up with quality control)
Down time problematic (technical support varies)
What are the three types of automated cell counters?
Impedance (particle) counters
Expanded buffy coat (QBC)
Flow cytometry (Lasercyte)
Describe how the Impedance (particle) Counters work.
Cells are suspended in electrolyte solution
Electric current passses through the solution
As cells pass through an aperture, it inhibits electrical conduction through the solution and then generates a pulse
Pulse generated is related to the particle size
Describe how the QBC works.
Blood is placed in a special tube that contains a powdered dye
Add the float (this actually expands the buffy coat)
Put the cap over the end
Put the tube in the centrifuge at high speed
As it spins, the cells settle during centrifugation based on their densities and the float present in the capillary tube expands the buffy coat by 10 times and the dye in the tube stains the cells
The machine scans with UV light
It records intensity of fluorescence of each layer (the thickness of the layers are converted to number quantities)
What are the layers of the QBC?
Monocytes and lymphocytes
Describe how a Flow Cytometry Analyzers work.
Cells pass through a laser beam
Light is scattered, creating a specific pattern for each cell type
Detectors note the pattern
What are the disadvantages of the Impedance Counter?
No reticulocyte data
Poor differentiation between the WBCs
Counts any nucleated cell (NRBC) as a WBC
Feline platelets (which are large) are counted as RBCs or even WBCs
Fibrin strands clog the machine
What are the advantages of the QBC?
efficient and economical (really cheap)
Fast (about 7 minutes)
What are the disadvantages of the QBC?
Designed to use with NORMAL blood
Cannot tell lymphocytes from monocytes
Cannot tell bands from segs
Can only use for certain species
Must fill capillary tube all the way
Underestimates frequency of leukopenia
What are the advantages of the Flow Cytometry Analyzer?
Ignores clumped cells
Can differentiate large platelets (cats) from WBCs
Does a 5-part differential, platelet count, reticulocyte count, and red cell indices
What are the disadvantages of the Flow Cytometry Analyzer?
Aggregates (clumping) of platelets may be counted as WBCs
Examination of a blood film is still always needed to detect morphology
What are the advantages of using a commercial lab?
Cheaper than in-house
Quality control programs
Films evaluated by experienced personnel
Consultation with pathologist
What are the disadvantages of using a commercial lab?
Takes time to get results
Make blood smears immediately, send along with EDTA blood
Species specificity (human labs)
What is automated cell counting?
Use for WBC count
Should never replace looking at a blood smear
Many give RBC count and red cell indicies as well
Can an automated cell counter give you the same information that reading a blood smear gives you?