We are a clinical flow cytometry laboratory in Milwaukee,
Wisconsin. We
diagnose many acute leukemias per year. Often we have encountered acute
myelogenous leukemias that stain positively with our monoclonal
antibodies
to CD41 and CD61, which indicates to us that this patient may have a
diagnosis of AML-M7. It is known that platelets adhere to blast cells
and
the standard recourse is to visually inspect the cells on a fluorescent
microscope for the adherence of the platelets to the blast cells. This
is often difficult, however, when the blast population is a minor
population within, say, bone marrow. I am looking for a method to show
that the binding of anti-CD41 and anti-CD61 to the blast cells is not
platelet adherence but true cellular staining by flow cytometry.
I have performed a literature search and have found two
references to this
phenomenon, including Blood, 79(9):2399-2403, 1992, and Blood
86(10):3771-3782 (1995). These papers noted the false-positive platelet
adherence to myeloid blasts and the second paper included a method using
5
mM EDTA to eliminate the binding of the platelets to the blasts. We
have
tried this method without success.
What have other members of the flow cytometry community done
with this
problem? Perhaps there is another method for preventing or eliminating
the binding of the platelets to the blasts? I would appreciate any
input
that I might receive with regards to this problem.
Thank you for your help with posting of this message and I hope
that the
flow cytometry community can provide some discussion of this topic.
Respectfully,
Cynthia B. Aller, Ph.D.
Director, Flow Cytometry Department
Medical Science Laboratories
11020 W. Plank Court
Suite 100
Wauwatosa, WI 53226
(414) 256-1480
FAX (414) 256-5589
email: caller@execpc.com
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