Clinical Flow Question

Virginia M Litwin virginia.litwin at
Tue Jul 10 15:31:35 EST 2001

Dear Clinical Flowers:

I have a perplexing clinical flow question.

We are using BD's MultiTEST with TruCount tubes - a single
platform assay--for lymphocyte immunophenotyping and absolute
counts.  BD has validated this assay with EDTA (a lyophilized
anticoagulant) whole blood. We did a comparison of EDTA and ACD,
and found that the ACD samples had much better stability at 48
and 72 h.  Most of the samples coming to my lab will be shipped
from investigative sites, so stability is an issue.

The problem is that ACD is a liquid anticoagulant (1 mL ACD and 6

mL blood) so my sample is diluted about 17% (if the tube is
completely filled).  When I compared the absolute counts from
whole blood collected in EDTA and ACD tubes from 10 healthy
volunteers, the difference was indeed 17%.    So my question is,
when I calculate the absolute cell counts,  should I correct the
cell count by 17% correction factor?   The problem is that the
tubes are not always filled to capacity.

Any thoughts on this dilemma?  I get the idea from "the
literature" that a lot of folks prefer ACD for flow and are
using single platform assays, but I haven't seen a single paper
where this question is addressed.

I'd appreciate your comments or suggestions.


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