cCD3 expression on granulocytes?
Anja.Porwit at mb.ks.se
Tue Jun 2 12:54:00 EST 1998
I think that problems with cyt.CD3 can depend on the method of
fixation/permeabilization and the MAb/conjugate used.
The immunophenotype in your case is more consistent with AML so I would do
the immunostaining on smears with APAAP before giving the T-ALL diagnosis.
For the last 4 years we have been using ORTHO Permeafix and CD3 PercP
from BD. Of the 90 cases of AML tested in only one there was a very weak
cyt CD3 by flow which was then confirmed negative by double APAAP on
smears. There is no background in normal monocytes or granulocytes.
I have heard from other collegues that CD3FITC can give unspecific staining
when used for cytoplasmic staining.
At 16.27 1998-05-29 -0400, you wrote:
>To all the clinical "Flow people" out there
>We have been using Caltag's fix & Perm kit for our cytoplasmic staining. So
>far we have had good results using TdT, MPO, cCD22, and cCD30. However,
>recently we had a challenging acute leukemia case with the following
>phenotype: CD45 mod+, CD7 partially+,CD11b (?)weak+, CD13 (?)weak+, HLA-DR+,
>CD34+, TdT+, CD38 bright+. Pertinent negatives included MPO, CD33, CD11c,
>CD14, CD15, CD10, CD19, cCD22, CD2, sCD3, CD4, CD8, CD5, CD56. We signed it
>out as T-cell acute lymphoblastic leukemia with aberrant myeloid expression
>mainly because of the TdT/cCD3 positivity combined with the MPO negativity.
>However, since we had just started using the cCD3, we did some more QC on
>normal lysed peripheral blood and found striking cCD3 positivity on our
>monocytes and granulocytes! I am really concerned about this finding and
>would like to find out from the experts if they have seen this in their
>labs. I also just received the CAP survey and noted that 25.7% of the labs
>reported cCD3 positivity on a otherwise pretty straight forward AML. Some
>of the labs (4.4%) even reported this out as ALL/T-cell type.
>Does this mean that 25% of the flow labs (including myself) have a problem
>with cCD3 staining? This would be kind of scary since it means (by trusting
>the cCD3 expression) that there is a chance of misinterpreting some cases as
>a T-ALL (with some myeloid expression) instead of an AML (with some CD2 or
>CD7 expression which is very common in AML's).
>I also should add that the patient was initially diagnosed at another
>reference lab with biphenotypic leukemia (they found essentially the same
>phenotype but also CD19, CD22, CD13 positivity). It sounds very unusual
>since I have never seen a case with myeloid, T and B markers. We are not
>sure if some non-specific positivity was overinterpreted or if one can see a
>very undifferentiated leukemia expressing all three lineages?
>Your feedback is much appreciated
>Dahl-Chase Diagnostic Services/Flow Cytometry
>333 State Street
>Bangor, Maine 04401
Department of Pathology
Karolinska Hospital, Stockholm
anpo at mb.ks.se
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