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

12 th Congress of the European Hematology Association
parison to platelet-free plasma. This observation is notable because,
when a platelet unit is transfused to a patient, a large quantity of
cytokines and chemokines is additionally infused. These biologically
active molecules may be possible mediators of post-transfusion immune
disorders, moreover a strong correlation between cytokines’ plasma levels
and transfusion reactions seems to exist. In fact, for example, ex vivo
production of sCD40L was quantified at levels sufficient to induce B cell
activation and differentiation. The inhibition of cytokine releasing during
the PLT storage could decrease the related transfusion reactions. In
order to increase transfusion safety, two procedures could be actually
and immediately carried out: the first one is represented by distributing
PLT concentrated as soon as possible after preparation (with only 1-2
days of storage); the second one consists in eliminating the residual
WBCs (and their cytokine secretion).
0848
ANTI-D ALLOIMMUNIZATION AFTER D-MISMATCHED ALLOGENEIC STEM CELL TRANS-
PLANTATION FOLLOWING REDUCED-INTENSITY CONDITIONING
N. Worel, 1 H.T. Greinix, 2 G. Körmöczi, 3 M. Mitterbauer, 2
A. Rosenmayr, 3 P. Kalhs, 2 P. Höcker4 1 Medical University, VIENNA; 2 BMT Unit, VIENNA; 3 Blood Group Serology,
VIENNA; 4 Transfusion Medicine, VIENNA, Austria
Background. Anti-D alloimmunization develops in up to 20% of RhDnegative
patients on chemotherapy following exposure to RhD antigen,
but is reported to be rare in recipients of haematopoietic stem cell transplants
(HSCT), especially following myeloablative conditioning. After
HSCT following reduced-intensity conditioning (RIC) rapid isohemagglutinin
production of donor lymphocytes have been observed in the
minor ABO-incompatible setting resulting in severe hemolysis. Aims.
The objective of this study was to evaluate the incidence of anti-D
alloimmunization after D-mismatched HSCT following RIC. Methods.
From 112 consecutive patients receiving RIC-HSCT between April 1999
and March 2006, 26 patients had a D-mismatched donor. Twelve RhDpositive
patients had an RhD-negative donor, 14 RhD-negative patients
received a RhD-positive graft. RIC consisted of the Seatle protocol (fludarabine
and 2 Gy total body irradiation;TBI) or the FLAMSA protocol
(amsacrine, fludarabine, cytarabine, cyclophosphamide, ATG and 4 Gy
TBI). For graft-versus-host disease (GvHD) prophylaxis cyclosporin A
(CsA) and mycophenolate mofetil (MMF) were given. From the day of
HSCT, red blood cell support consisted of donor Rh-type RBCs. Results.
After a median follow-up of 30 months, 16 of 26 patients with a D-mismatch
donor were alive. Two RhD-negative patients died within 10
days after HSCT and were not evaluable for anti-D alloimmunization.
Eight patients developed acute GvHD between days 7 and 52 and 11
patients chronic GvHD between days 75 and 274 after HSCT, respectively.
RhD-positive patients with RhD-negative donors received a median
of 11 (range, 0-92) RhD-negative RBC units during a median of 8
months (range, 0-38) after HSCT. RhD-negative patients with RhD-positive
donors were transfused with a median of 11 (range, 0-44) RhD-positive
RBC units during a median of 2 months (range, 0-54). There was
no difference in transfusion requirements between D-mismatched vs. Dmatched
patients. After a median of 13 months (range, 0-73) only in 1
RhD-positive patient with an RhD-negative donor an anti-D antibody
was detected. This patient received 2 units of RhD-negative RBCs 5
days after HSCT and never experienced acute or chronic GvHD. Conclusions.
Fludarabine based RIC and CsA with MMF given post transplant
prevents anti-D formation in RhD-negative recipients of an RhD-positive
graft. However, anti-D developed in an RhD-positive recipient of an
RhD-negative graft who never was exposed to RhD-positive blood products
after HSCT. This may be caused by the relative high amount of
residual RhD-positive RBCs at the time of transplant and an immunosuppressive
regimen with CsA and MMF were donor B-cells can escape
T-cell control as seen in the minor ABO-incompatible setting. Therefore,
patients with an RhD-mismatched donor should routinely be tested for
RhD alloimmunization in the post-transplant course.
316 | haematologica/the hematology journal | 2007; 92(s1)
UCB transplantation & mesenchymal stem cells
0849
CELLULAR RECOVERY AFTER MANIPULATION IN 27 UNITS OF UMBILICAL CORD
F. Zinno, 1 F. Landi, 1 V. Aureli, 1 M. Caniglia, 2 I. Rana, 2 R.M. Pinto, 2
M.J. Miele, 2 P. Ciaffi, 2 C. Capponi, 2 G. Isacchi1 1 2 Tor Vergata University, ROME; Bambino Gesù Pediatric Hospital, ROME,
Italy
Background. The success of an allogenic graft with placental blood is
directly linked to the cellular dose, both of nucleated cells (NC) and
CD34 + (CD34 + ) cells, infused. It is therefore essential that the thawing
method allow for recovery of as much NC and CD34 + as possible. Aims.
Our study examines the results our Center obtained when assessing
recovery of NC, CD34 + , and cellular viability. Methods. From January
2000 to October 2006 our Center performed 27 allogenic grafts with
units of placental blood from several different umbilical cord banks.
Thirteen patients had ALL, 4 had AML, 3 had myelodysplasia, 3 had histiocytosis,
2 had NHL, 1 had Fanconi’s Anemia and 1 had Chediak-
Higashi Syndrome. Median weight for these patients was 22.5 Kg (range
6-72). The Rubinstein protocol was used for thawing. Nucleate cell count
was performed using an electronic cell counter while CD34 + and viability
was assessed with flow cytofluorometry. Results. (All values given are
median) The volume of the units before thawing was 120 mL. (25-278),
following manipulation of 127 mL (35-385). The NC went from 161×10 7
(75.6×10 7 - 290×10 7 ) to 123×10 7 (50×10 7 -230×10 7 ), with a 77.8% recovery
rate (56.4-96.7). Recovery rate for CD34 was 91.4% (25.1-121.4) inasmuch
as before manipulation the units contained 5.9×10 6 (1.3×10 6 -
19.9×10 6 ) while after thawing the recovered CD34 + were 5.1×10 6
(1.2×10 6 -10×10 6 ); in one case recovery was higher than 100%, due to the
fact that the first measurement of the CD34 + was performed at a different
center that uses different instruments and a different protocol. Postthaw
viability was 85% (60-98). Patients received 5.3×10 7 /Kg (2.1×10 7 -
14.8×10 7 ) NC and 0.2×10 6 /Kg (0.1×10 6 -1.7×10 6 ). Conclusions. Our study
showed that the Rubenstein protocol is the best method for manual
thawing; in all the cases cellular recovery obtained an optimal cellular
dose with which to perform a graft and cellular viability was always
high.
0850
MESENCHYMAL STEM CELL MEDIATED IMMUNOSUPPRESSION IS NOT CONFINED TO
PROGENITOR STATUS
P. Jones, N. Horwood, A. Cope, F. Dazzi
Imperial College London, LONDON, United Kingdom
Although it has been widely demonstrated that mesenchymal stem
cells (MSC) exert potent immunosuppressive effects, there is little information
as to whether more mature mesenchymal stromal cells (SC)
share the same property. Accordingly, we set out to test the ability of
SC from different tissues to inhibit the proliferation of peripheral blood
mononuclear cells (PBMC) exposed to polyclonal stimuli. Chondrocytes,
along with fibroblasts from synovial joints, lung and skin were used as
a source of SC. Irrespective of their differentiation potential and/or content
of progenitor cells, SC from all tissues exhibited powerful anti-proliferative
functions. This was in marked contrast to the parenchymal
cells tested. Although SC did not interfere with early T lymphocyte activation,
they arrested T cells in the G0/G1 phase of the cell cycle after
stimulation and rescued them from apoptosis. In addition, IFNγ and
TNFα production was reduced by the presence of SC in stimulated T cell
cultures. We observed that the inhibitory effect is ultimately mediated
by soluble factors, the production of which requires SC to be licensed in
an inflammatory environment by cell contact. We conclude that the
immunosuppressive effect of mesenchymal cells is not confined to multipotent
stem cells but is a fundamental characteristic of all stroma. Our
data suggests that SC, appropriately licensed, regulate T cell homeostasis.