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OCTOBER 16-18, 2011 • PORTLAND, OR
P11
Bimodal Bcl-2 Expression in CLL: Inter- and Intra-
clonal Heterogeneity
Heba A. Degheidy, Shahinaz Gadalla, Mohammed
Z.H Farooqui, Fatima Abbasi, Steven Bauer, Adrian
Wiestner, Stetler-Stevenson MA, Marti Gerald
Bethesda, MD, USA
Introduction. Bimodal distributions of bcl-2 in deletion
13q14.3 chronic lymphocytic leukemia (CLL) cases
were examined. Material & Methods. Multi-color
fow cytometry panel of CD3/CD5/CD19/CD20/anti-
lambda/anti-kappa and anti-bcl-2 was used. Bcl-2
index (MFI of the CLL clone/MFI of residual T-cell)
was evaluated in ffty-four untreated CLL/MBL cases.
Cell sorting and Interphase FISH were performed on
selected cases. Results. Of the 54 cases, 33 cases
had 13q14.3 deletion, and 21 cases were designated
as non 13q14.3 deletion. Bcl-2 index of ≥1.75 strongly
predicts 13q14.3 deletion status (OR=16.75, and
p=0.0002). Detailed analysis of bcl-2 expression of
del 13q14.3 cases revealed that 7/33 cases showed
bimodal bcl-2 expression. Group I (n=3,
Intra-clonal
bcl-2 heterogeneity) cases showed a difference in
bcl-2 expression within their CLL clonal cells. Group
II ( n=4,
inter-clonal
bcl-2 heterogeneity) cases
showed difference in bcl-2 expression based on CD20
expression( bright(br), and dim) sub-populations.
In Group I cases with a mixture of hemizygous and
diploid CLL cells, sorting showed enrichment of
hemizygous cells in bcl-2 br population. In one Group
I case that showed a mixture of hemizygous and
homozygous del 13q14.3 in the CLL clone, sorting
led to enrichment of homozygous cells in bcl-2 br
population. Interphase FISH analysis on Group II
sorted cells showed enrichment of either hemizygous
or homozygous in one of the CLL subpopulations.
Conclusion. Intra-clonal and inter-clonal bcl-2 bimodal
expression profles identify sub-populations with
varying amounts of either hemi- or homozygous del
13q14.3. Further studies are required to isolate pure
hemizygous or homozygous, from diploid CLL sub-
populations.
POSTER ABSTRACTS