Week 5: Electronic Cell Counters

• Instrumentation

• Automation

• Electric impedance

• Coulter principle

• 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

H-6000; 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