CD34 viability

Ruud Hulspas ruud-hulspas at cytonome.com
Fri Jan 4 10:08:53 EST 2008


Hi Suzie,

You raise an interesting question. What exactly would you like to 
measure - (1) the percentage of viable CD34+ cells relative to the total 
number of (nucleated) cells, or (2) the percentage of viable CD34+ cells 
relative to the total number of CD34+ cells ?
I am not so sure if it is possible to measure (2), because it requires 
measuring dead cells that express CD34. We've had numerous discussions 
about antibody specificity on viable cells, but never really focused on 
dead and dying cells. Are all surface markers still intact on cells with 
compromised membranes ? I wouldn't be surprised if many antibodies don't 
recognize their target any longer when the membrane is compromised (i.e. 
7AAD or PI is able to get into the cell). In that case, one would obtain 
a false high viability result.
For the same reason, it may be that antibodies bind more 
'non-specifically' to cells with compromised membranes and in that case, 
one would obtain a false low viability result.
The only accurate number obtainable by flow cytometry is number of 
viable cells. "Viability" is tricky, especially relative to an 
antibody-labeled subpopulation of cells.

Ruud

-- 
<http://www.cytonome.com>     Cytonome <http://www.cytonome.com>
Dr. Ruud Hulspas, Ph.D.
Director of Cytometry

Cytonome <http://www.cytonome.com>
27 Drydock Avenue
Boston,  MA 02210
phone: 617-330-5030 x226
fax: 617-330-5031
Ruud-Hulspas at cytonome.com <mailto:ruud-hulspas at cytonome.com>
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