Re: CD34 counting: Partec vs. BD TruCount

Dear Dr. Jakso,

as addition to the observations you have submitted, I would like to  
point to a new study which investigates the influence of different  
lysing reagents in CD34 counting:


Greve, B. et al.:
The impact of erythrocyte lysing procedures on the recovery of	
hematopoietic progenitor cells in flow cytometric analysis
StemCells (October 2005, Impact Factor 5.5)

Abstact:
Since preanalytic lysing of erythrocytes remains critical in flow  
cytometry, we investigated the influence of four lysing procedures on  
the quantification of leukocyte and CD34+ cells in hematopoietic cell  
transplants (HCT). Samples were derived from stem cell enriched  
mobilized whole blood collected by apheresis (unselected) and  
immunologically purified stem cell products (selected) and were  
measured using the dual platform (2-PF) method utilizing two flow  
cytometric systems. Additionally, cells were measured by a volume- 
based technique (single platform (1-PF)). Results were identical in  
the 2-PF mode (unselected HCTs: r = 0.998, selected HCTs: r = 0.999).  
In comparision to the 2-PF results, the 1-PF measurements revealed a  
mean decrease of 59.5 % of CD34+ cells (50.8 % CD45+ cells) in	
unselected HCTs and 52 % (49.8 % CD45+ cells) in selected HCTs. In  
order to check the accuracy of cell quantification in the 1-PF	
method, leukocyte reference values from hematology counter results  
were compared to flow cytometric (1-PF) counted nucleated cells. This  
analysis revealed a good congruency of r = 0.998 (unselected HCTs)  
and r = 0.999 (selected HCTs). In conclusion, all used lysing  
procedures induced substantial loss of leukocytes and CD34+ cells. As  
demonstrated by the high accuracy in the 1-PF technique, all  
erythrocyte lysing procedures caused significant cell loss which led  
to inconsistent counting of CD34+ cells in non-volumetric flow	
cytometric (2-PF) protocols.

The article is available online at:
http://stemcells.alphamedpress.org/cgi/content/abstract/2005-0269v1

Best regards

Roland Göhde
Partec GmbH