title: The depletion of T cells from haematopoietic stem cell transplants.
abstract: 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.
authors.affiliation: CLB, Sanquin Blood Supply Foundation, Department of Transfusion Technology, Academic Medical Centre, University of Amsterdam, The Netherlands.
authors.forename: I C
authors.initials: IC
authors.lastname: Slaper-Cortenbach
authors.forename: M J
authors.initials: MJ
authors.lastname: Wijngaarden-du Bois
authors.forename: A
authors.initials: A
authors.lastname: de Vries-van Rossen
authors.forename: H P
authors.initials: HP
authors.lastname: Borst
authors.forename: H
authors.initials: H
authors.lastname: van der Lelie
authors.forename: H G
authors.initials: HG
authors.lastname: van Heugten
authors.forename: L F
authors.initials: LF
authors.lastname: Verdonck
authors.forename: N M
authors.initials: NM
authors.lastname: Wulffraat
authors.forename: P M
authors.initials: PM
authors.lastname: Hoogerbrugge
mesh_terms: 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*
chemical_list: D018952:Antigens, CD34; D018801:CD2 Antigens; D017252:CD3 Complex