Week 5: Electronic Cell Counters
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Instrumentation
Automation
Electric impedance
Coulter principle
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Optical scatter
Myeloperoxidase
Radio frequency probe
Histogram
Data plot
Instrumentation/Automation
• Increase productivity and precision
• Accuracy still depends on operator
• Other interventions
• Calibration
• QC
• Maintenance
Brief History
• 1852: Hemocytometry by K Vierordt
• 1956: Electronic impedance counter Coulter
Model A
• 1970’s: Light scatter technique (e.g., Ortho
ELT-8
• 1980’s: Cytochemical counter Technicon H6000; flowcytometry
• 1990’s: VCS technology of Coulter STKS
Electrical
Impedance
• Coulter principle first
developed in 1950’s
R = k x Particle volume
Aperture size
Coulters A, F, ZBI
Coulters S and S-Plus
Light Scatter
• Degree of light scatter is proportional to cell
size
• Use of laminar flow using sheath fluid
prevents cells from tumbling
• More precise cell grouping with size:
differential count
Ortho ELT-8
Cytochemical
• Technicon measured the myeloperoxidase
activity of leukocytes along with light
scatter to differentiate leukocytes more
precisely
• Development of flowcytometry: cell marker
studies, DNA analysis, etc.
Light Scatter and Myeloperoxidase Activity
Radio Frequency Probe
• VCS (volume, conductivity, scatter)
technology by Coulter
• Radio frequency probe with impedance by
Sysmex
• Able to determine cell surface features and
internal (nuclear, granular) complexity
Sizing and Conductivity