Flow Cytometry Cell Counting Beads

Many flow cytometers cannot directly provide the cell concentration or absolute count of cells in a sample. Absolute cell counts are generally obtained either by combining a separate cell concentration determination from a hematology analyzer with flow cytometric population data (multiple platform testing) or by adding an internal microsphere counting standard to the flow cytometric sample (single platform testing). Life Technologies now offers CountBright™ Absolute and AccuCheck flow cytometry cell counting beads.

CountBright™ Absolute Counting Beads

CountBright™ Absolute flow cytometry cell counting beads are a calibrated suspension of microspheres that are brightly fluorescent across a wide range of excitation and emission wavelengths and contain a known concentration of microspheres. Countbright ™ Absolute flow cytometry cell counting beads are similar in size to lymphocytes, so they do not require any changes in instrument settings. For absolute counts, a specific number of counting beads are added to a known volume of sample, so the sample volume per bead is known. The number of beads in a sample tells you the volume analyzed, and allows accurate calculation of cells per microliter in the sample.

The CountBright Absolute flow cytometry cell counting beads give you:
  • Compatibility—with every commercially available instrument because they are loaded with a wide breadth of fluorochromes,
  • Versatility—easy to use protocol that works with multiple cell types including lyse/no wash whole blood
  • Accuracy—more reliable than multiple platform testing

Figure 1. Determination of live and dead cells and absolute cell number. Plot of calcein fluorescence collected with a 530/30 nm bandpass filter vs. ethidium homodimer-1 fluorescence, collected with a 610/20 nm bandpass filter, showing clear separation of live and dead cells, as well as counting beads. A mixture of live and heat-killed Jurkat cells (human T cell leukemia) was treated with the reagents in the LIVE/DEAD® Viability/Cytotoxicity Kit; CountBright™ Absolute Counting Beads were added, and the sample was analyzed by flow cytometry using 488 nm excitation.


Description
Ex (nm)
Em (nm)
Quantity
Cat. No.
CountBright™ Absolute Counting Beads
UV-635
385-800
5 mL
C36950

AccuCheck Counting Beads

AccuCheck flow cytometry cell counting beads are ideal for clinical applications.  They offer a single-platform method for absolute cell counts that combines the advantages of direct flow cytometric immunophenotyping with the use of two different fluorescent beads that serve as a double internal control for pipetting and  mixing.  A known volume of AccuCheck flow cytometry cell counting beads is added to a known volume of cell sample and the beads are counted along with the cells.  Since the concentration of the beads is known, the number of cells/µL is obtained by relating the number of cells counted to the total number of fluorescent bead events.

The AccuCheck Counting Beads give you:
  • Accuracy—internal control using ratio of two different color beads indicates pipetting accuracy
  • Reliability—Single Platform is preferred over  multiple platform testing leading to consistency in results
  • Compatiblity—Easy to validate with most immunophenotyping experiments


Description
Ex (nm)
Em (nm)
Quantity
Cat. No.
AccuCheck Flow Cytometry Counting Beads
Bead A: 488
Bead B: UV-635
Bead A: 525-670
Bead B: 525-670
10 mL
PCB100