In vitro diagnostics and laboratory technology

CD4+ T-Cell counting Technology

What are CD4 T-cells?

CD4+ T-cells are also known as helper T-cells and act as an co-ordinator of the immune response, unfortunately, CD4+ T-cells are also the main targets of HIV. HIV destroys infected CD4+ T-cells and leading to an overall weakening of the immune system.

What is the CD4+ T-cell count?

Lower numbers of circulating CD4+ T-cells indicates a weakening of the immune system and advancement in the progression of HIV disease. The CD4+ T-cell count can also be indicative of the success or failure of anti-retroviral therapy (ARV).

How are CD4+ T-cells enumerated?

CD4+ T-cell counts are performed using manual and automated methods.

Manual

Microscopy

  • Optical or fluorescence microscopy
  • Requires a centrifuge and other laboratory consumables e.g. beads
  • Designed for low sample throughput laboratories in resource-limited settings
  • Currently marketed products include; Cyto-Spheres [Coulter Corporation, USA] and Dynabeads® [Dynal Biotech, Norway]
Automated Systems

Flow Cytometery

  • Gold Standard for accuracy, precision, reproducibility
  • Expensive and technically demanding, requiring extensive technician training
  • Capable of high sample throughput in well-resourced laboratory
  • Can be used for other laboratory applications
  • Requires regular equipment maintenance

Dedicated Cytometer

  • Cytometer used exclusively to perform CD4+ and CD8+ T-cell enumeration
  • Simpler and cheaper than flow cytometers but lacking in general laboratory versatility
  • Currently marketed products include; FACSCount™ [Becton Dickinson, USA]
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