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ICCS 2012
to 74.6% respectively. Interestingly, 0/9 (0%) cases with no prior
exposure to chemotherapy were positive while 8/35 (22.9%)
post-chemotherapy cases were positive. These preliminary
findings raise the possibility that aberrant expression of CD2
and/or CD25 may be seen on mast cells outside of the setting of
SM, in particular during active marrow regeneration.
P11
UTILITY OF CD200 IN THE DIAGNOSIS OF CHRONIC
LYMPHOCYTIC LEUKEMIA
Sindhu Cherian
1
, Sandra Bohling
2
, Megan Wilson
1
, Greg Levin
1
,
Brent Wood
1
1
University of Washington,
2
PhenoPath Laboratories
Chronic lymphocytic leukemia/small lymphocytic lymphoma
(CLL/SLL) is an indolent CD5+ B cell lymphoma in which
flow cytometry plays an integral role in diagnosis. Mantle cell
lymphoma (MCL) is often in the differential when considering
CLL/SLL, and distinguishing the two is clinically important.
Typically, the two can be distinguished using evaluation
of CD20, CD23, surface light chain intensity, and FMC7
expression; however, additional markers are required in some
cases. In the current study, we evaluate the utility of mean
fluorescent intensity (MFI) of CD200 to separate CLL/SLL and
MCL and compared CD200 to other established parameters.
66 consecutive cases of CD5+ B cell lymphoma with clinical
and/or morphologic data compatible with a diagnosis of CLL/
SLL (n=51) or MCL (n=15) were included. A MFI ratio (defined
as MFI of parameter X for CD5+ B cells/MFI of parameter
X for T cells) was calculated for CD200, CD20, CD23, and
FMC7. Expression of each parameter was different between
MCL and CLL/SLL with a p value of <0.05; however, the
difference for CD200 had the lowest p value with only 2 outliers
identified. In addition, an initial assessment of monoclonal B cell
lymphocytosis (n=14) and CD5+ diffuse large B cell lymphoma
(n=3) found variable CD200 expression. An ROC curve
analysis indicates that most cases of CLL/SLL and MCL can be
separated using a cut off of 1.10 for the CD200 MFI ratio (area
under the curve of 0.982). Follow up studies are in progress
and will focus on characterizing outlier cases and applying the
CD200 MFI ratio to a validation set.
P12
FLOW CYTOMETRIC TESTING FOR PAROXYSMAL
NOCTURNAL HEMOGLOBINURIA: CD64 IS BETTER FOR
GATING MONOCYTES THAN CD33
Bakul I Dalal, Nikisha S Khare
Flow Cytometry Service, Division of Laboratory Hematology,
Vancouver General Hospital
Background:
Paroxysmal nocturnal hemoglobinuria (PNH) is
characterized by the absence of glycosyl phosphatidyl inositol
(GPI)-associated ligands in neutrophils, monocytes, and
red blood cells. Monocytes can be separated by their bright
expression of either CD33 or CD64. We report a comparison
of CD33- vs CD64-based monocyte gating in flow cytometric
testing for PNH.
Methods:
119 cases tested for PNH, following
the flow cytometry technic recently recommended by the
international panel (Borowitz et al, Cytometry Part B: Clinical
Cytometry, August 2010), were reviewed. The number of
monocytes and their GPI-deficient fraction gated with CD33
and CD64 were compared. The clustering patterns were
recorded and investigated when necessary.
Results:
CD64
staining showed distinct separation of the monocyte cluster
from lymphocytes; while CD33 staining showed a bridge of
CD33-dim events (fig-1), likely consisting of basophils, dendritic
reticulum cells, promonocytes, or granulocyte precursors in
90% of cases, making precise gating somewhat subjective. The
difference between the number of monocytes gated by CD33
and CD64 ranged from -26% to +32% (average: 1.69%). Six
patients had GPI-deficient monocytes by both CD33 and CD64-
POSTER ABSTRACTS