re Peripheral blood CD 34 counts used in assessing apheresis collections
D. Robert Sutherland
rob.sutherland at utoronto.ca
Wed Mar 27 17:08:47 EST 2002
A few years ago Peter Chapple and colleagues published a paper (Bone
Marrow Transplant 1998 Jul;22(2):125-30) suggesting that if the PB
contains 5 or more CD34+ cell per microlitre, then one can expect to
collect at least 0.5 x 10e6 CD34+ cells/Kg patient weight, regardless of
age sex and other unmentionables.
We use the single platform ISHAGE protocol (aka 'Stem-Kit') for all our
CD34+ cell enumerations in the auto PBSC transplant program.
Typically, a patient will come in after mobilisation and have blood
samples drawn in the morning. From one sample, we obtain an absolute
leukocyte count from an automated hematology analyser. We stain the
other and analyse it (usually) within 35 minutes of collection and
report the data back to the apheresis unit. From the same sample tube as
we obtain the absolute CD34+ cell count, we also derive the absolute
CD45+ cell (leukocyte) count. As an internal check, we compare these
numbers. They should be (and almost invariably are) in very close
agreement. If we find 5 or more CD34+ cells per microlitre in the PB
sample (based of course on counting at least 100 CD34+ cells), the
patient is usually sent for collection. If there are fewer than 5, we
usually do not collect them.
After collection (and sometimes also during collection) we obtain an
aliquot of the product, dilute it 1:10 and obtain a wbc from the
hematology analyser. This serves two functions: It tells us whether we
need to further dilute the sample prior to flow analysis (max wbc should
be about 30,000/microlitre). It also allows the comparison of the
absolute wbc with the flow CD45+ cell count as above for the PB sample.
We perform another absolute CD34+ cell enumeration, and 40 minutes later
the data is reported to the apheresis unit. On the basis of these
numbers, it is decided whether more collections are needed, or in some
cases, how much longer the patient needs to be apheresed, so that
sufficient cells can be collected in order to obviate further
The routine use of such procedures has greatly reduced the number of
'failed collections', and significantly decreased the average number of
collections per patient to obtain our target CD34+ cell dose of 5 x 10e6
viable (pre-cryo) CD34+ cell per Kg.
I have attached a couple of graphs showing our correlations between (1)
PB and apheresis CD34+ cell numbers, and (2) hematology analyser WBC
versus CD45+ cell counts. These data show that if we have 10 CD34+
cells/microlitre in the PB, then we can expect to get about 1 x 10e6
CD34+ cells per Kg in the collection. Our apheresis unit uses a Cobe
Spectra running version 4.0 software. Other versions of the software
may not give you the same 'mileage'.
I hope this helps.
University Health Network
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