12th Congress of the European Hematology ... - Haematologica

1011
FLOW CYTOMETRIC DNA INDEX AND KARYOTYPE ARE COMPLEMENTARY IN CHILDHOOD
ACUTE LYMPHOBLASTIC LEUKEMIA
P. Rachieru, 1 L. Baranger, 1 N. Dastugue, 2 A. Robert, 2 F. Genevieve, 1
E. Kuhlein, 2 A. Chassevent 3
1 C.H.U. Angers, ANGERS, France; 2 C.H.U.Toulouse, TOULOUSE, France;
3 CRLCC Paul Papin, ANGERS, France
Background. DNA index (DI), which expresses the blast cells DNA
content, is a prognostic factor in childhood acute lymphoblastic leukemia
(ALL). When the leukemic clone does not show pejorative structural
abnormalities, a better survival is associated with a DI > 1.16 (equivalent
to a modal number higher than 53 chromosomes). On the other
hand, a hypodiploid clone (≤34 chromosomes) induces a poor prognosis.
Associated with the clinical and molecular characteristics, these
parameters are used to include the patients in different therapeutic schedules.
Aims. The aim of this study was to validate the accuracy of the
flow cytometric (FCM) DNA index (DI) by confrontation with the karyotype,
in order to provide a useful information at diagnosis in case of discrepancies
between these two results. Methods. One hundred and twelve
patients (51 girls and 61 boys) treated between 1990 and 2006 (CHU
Angers and Toulouse) were included in this retrospective study. Samples
were obtained at diagnosis from bone marrow (109 samples) or blood
(3 samples). Depending on the sex, megabases number of each normal
chromosome is a definite percentage of the total sum of the 46 chromosomes
of diploid genome. Thus, X and Y chromosomes concern respectively
2.58% and 0.93% of a 46,XY cell DNA content. According to this
information, we created a formula to calculate a theoretic DNA index
(tDI) based on the blast cell karyotype. For every patient, the calculated
tDI took into account the additional or missing chromosome material of
the major clone. Results. In a linear regression study, DNA index correlated
with modal chromosomes number (y=0.0202x+0.0685 and
R=0.992) and with tDI calculated from karyotype (y=0.9709x+0.033 and
R=0.995). Technical reasons may compromise the leukemic clone characterization
obtained with karyotype (insufficient in vitro blast cells
growth induced by poor cellularity or low S phase). FISH and molecular
biologic methods may overcome the karyotype failure, but DNA
index can alert and guide in this step (3 cases in this study). In addition,
we present three cases containing 2 blast cell populations with FCM, one
hypodiploid (DI=0.56, 0.73 and 0.77) and the second hyperdiploid
(DI=1.11, 1.33 and 1.53 respectively). In the three cases, the karyotype
detected only the hyperdiploid clone. Considering the pejorative prognosis
of high hypodiploidy, DNA index was very useful to confirm the
profile of triploidy/duplication of hypodiploidy 30-40 chromosomes
obtained with the karyotype. Conclusion. The strong correlation between
tDI and DNA index validates the accuracy of FCM quantification, which
is technically fast and could be performed on fresh or frozen samples. If
karyotype is essential to analyze chromosomal abnormalities (numerical
and structural), FCM provides complementary informations when the
leukemic clones express abnormal chromosomes number or heterogeneity
in DNA index. We conclude that DNA index is a useful tool in the
ploidy characterization of blast cells and that it should be transmitted to
the cytogeneticist as soon as possible at diagnosis of childhood ALL.
1012
INTERLEUKIN-6 (IL-6),TUMOR NECROSIS FACTOR α (TNF-α) LEVELS AND IL-6,
TNF-POLYMORPHISMS IN CHILDREN WITH THROMBOSIS
S. Unal, 1 S. Aytac, 2 F. Gumruk, 2 D. Yalnizoglu, 2 A. Gurgey2 1 2 Hacettepe University Faculty of Medicine, ANKARA; Hacettepe University,
ANKARA, Turkey
Infection has an important role in the pathogenesis of thrombosis and
it becomes more prominent in childhood cases, where the infection frequency
is higher. It was suggested that patients with high TNF-α and IL-
6 levels might be at increased risk of developing thrombotic complications
due to the effects of these cytokines on the coagulation pathway.
Functional polymorphisms in the promoter regions of the genes coding for
TNF-α and IL-6 are associated with increased plasma levels of these
cytokines. In this study, we planned to evaluate the serum levels of acute
phase reactants such as CRP and of cytokines such as TNF-α, IL-6, and we
aimed to investigate the association between the TNF-α -308 G/A and IL-
6-174 G/C polymorphisms in Turkish pediatric patients with thrombosis.
Fifty-eight children with thrombosis (Group 1) and 89 controls (Group 2)
were included in the study. Patients who had a history of infection within
the fifteen days prior to thrombosis were classified as Group 1a and
those who had no infection history prior to thrombosis were classified as
Group 1b. Serum TNF-α did not differ significantly between the groups.
However, IL-6 level was higher in group 1a than in group 1b (p