-----Messaggio originale-----
Da: Adriano Venditti [SMTP:avendtti@pelagus.it]
Inviato: venerdì 16 gennaio 1998 19.50
A: Cytometry Mailing List
Oggetto: R:Further CD45-negative acute leukemia
I think we need to have a common language when talking about "biphenotypic leukemia". This definition, in my opinion is a little bit confusing as it refers to a broad spectrum of leukemias; from those with a minimal phenotypic deviation to the so called "genuine" biphenotypic leukemia. The case presented by Chang sounds like an ALL with phenotypic deviation as suggested by the expression of CD13 and CD33. On the other hand, the diagnosis of "genuine" biphenotypic leukemia requires the presence of MPO (as revealed by moabs or at ultrastructural level) and that of cytoplasmic CD3 or CD22/CD79a. So I would classified the leukemia presented by Chang as a "genuine" biphenotypic leukemia if it expressed MPO plus cytoplasmic CD22 or CD79a. At the moment it remains an ALL with deviant expression of myeloid antigens. In this view I do not agree with Daniel when he says that MPO is not essential for the diagnosis of biphenotypic leukemia. We have, in several publications (Br J Haematol 1994, Blood 1997, Ann Haematol 1997), demonstrated that indeed it is essential for the diagnosis of minimal differentiated acute myeloid leukemia (AML-M0) which sometimes lacks CD13 or CD33. Again, we need a common language and more importantly, strict criteria to define a biphenotypic leukemia which is, in my opinion, a different condition than the simple deviant expression of antigens belonging to other lineages.
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Da: Daniel Arber[SMTP:darber@smtplink.Coh.ORG]
Inviato: mercoledì 14 gennaio 1998 22.35
A: Cytometry Mailing List
Oggetto: Re: Further CD45-negative acute leukemia
I would agree that MPO is not essential for a diagnosis of
biphenotypic acute leukemia, but the EGIL scoring recommendation
requires more than two points for myeloid antigens to call a case
biphenotypic. The expression of CD13 and CD33 are worth a total of 2
points and another myeloid marker would be needed before calling the
case biphenotypic.
Dan Arber
City of Hope
______________________________ Reply Separator _________________________________
Subject: Further CD45-negative acute leukemia
Author: <kcdol@samsung.co.kr > at INTERNET
Date: 1/14/98 11:20 PM
Dear flowers
I really appreciate for many experts' valuable comments
regarding CD45-negative acute leukemia.
Now that CD45-negative acute leukemia is not uncommon,
I would like to ask another question.
CD45, a protein tyrosine phosphatase, is known to be important
in regulation of cellular proliferation that is there any
evidence of the relation between leukemogenesis and CD45-negativity?
And today, we tried more monoclonal antibodies on those CD45-negative
leukemic cells that got following results;
MPO(-), CD45RA(-), CD45RB(-), CD45RO(strong positive)
on paraffing bone marrow section.
Another question I have is
Is MPO positivity essential to diagnose the acute biphenotypic leukemia?
Since EGIL working group suggested that in diagnosing acute biphenotypic
leukemia, MPO is the most valuable one but both CD13 and CD33 positivity
without MPO could be used as markers for acute biphenotypic leukemia.
Thanks again for your excellent comments.
---------------------------------------
---------------
Chang-Seok Ki, MD
3rd-year Resident
Dept of Clinical Pathology
Samsung Medical Center
Tel. 82-2-3410-2707
Fax. 82-2-3410-2719
E-mail. kcdol@samsung.co.kr
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