The depletion of T cells from haematopoietic stem cell transplants.
OBJECTIVE
In our laboratory, we have developed an immunorosette technique for the depletion of T cells from bone marrow transplants. Tetrameric complexes of monoclonal antibodies are able to form very stable immunorosettes, which are efficiently depleted with the aid of a blood cell separator. Major improvements over the original sheep red blood cell depletion are the use of human (patient or donor derived) erythrocytes instead of sheep-derived cells, and the possibility of using a closed system for separation in a cell separator. In contrast to bone marrow, mobilized haematopoietic stem cell transplants obtained after leucocytapheresis contain higher numbers of T cells. Therefore, a different approach is necessary.


METHODS
We have used two CD34 selection systems (Isolex 300SA and the Clinimacs) to perform T-cell depletions from peripheral blood stem cell (PBSC) transplants.


RESULTS
Immunorosette T-cell depletion, with CD2/CD3 tetrameric complexes, of bone marrow transplants resulted in a mean 2.5 log depletion of T cells with a yield of 50% of the CD34+ cell population. Stem cell selection of PBSC transplants using one of the CD34 selection procedures resulted in a 4.5 log depiction of T cells for both systems, but with different results for the recovery of CD34+ cells. An increased yield of CD34+ cells was obtained with the Clinimacs procedure (57.9+/-9.0%) in comparison to the Isolex procedure (40.1+/-12.5%).


CONCLUSIONS
Our own immunorosette depletion technique and the two tested CD34 selection methods for stem cell transplants both resulted in a very efficient T-cell depletion with the recovery of 40-60% of the CD34 haematopoietic stem cells present in the transplant.
Slaper-Cortenbach
I C
IC
CLB, Sanquin Blood Supply Foundation, Department of Transfusion Technology, Academic Medical Centre, University of Amsterdam, The Netherlands.
Wijngaarden-du Bois
M J
MJ
de Vries-van Rossen
A
A
Borst
H P
HP
van der Lelie
H
H
van Heugten
H G
HG
Verdonck
L F
LF
Wulffraat
N M
NM
Hoogerbrugge
P M
PM
D018952:Antigens, CD34 / Q000378:metabolism; D001171:Arthritis, Juvenile / Q000628:therapy; D001854:Bone Marrow Cells / Q000166:cytology; D018801:CD2 Antigens / Q000378:metabolism; D017252:CD3 Complex / Q000378:metabolism; D002648:Child; D018380:Hematopoietic Stem Cell Transplantation / Q000379:methods*; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D008212:Lymphocyte Depletion / Q000379:methods*; D013601:T-Lymphocytes / Q000166:cytology* / Q000378:metabolism; D019172:Transplantation Conditioning / Q000379:methods*
D018952:Antigens, CD34; D018801:CD2 Antigens; D017252:CD3 Complex