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An advantage of CD34+ cell selection over antibody purging is that a component allograft is produced comprising a stem cell enriched and an unadsorbed fraction, the latter containing T cells which may be used for post-transplant immunotherapy. Initial reports with PBSC allografts suggested that T cell depletion (TCD) by CD34+ cell selection and post-graft cyclosporin A +/- methotrexate was insufficient prophylaxis against acute GVHD. We compared sequential TCD (of a CD34+ cell-selected fraction) using a second (CD2) immunoaffinity step or Campath-1M monoclonal antibody and complement. Since a high stem cell 'dose' enhances engraftment across HLA barriers and improves overall post-transplant outcome, the recovery of CD34+ cells and progenitors were assessed. Sequential positive (CD34+) and negative (CD2+) immunoaffinity selection resulted in a 3.4 log depletion of T cells as compared to a 4.05 log depletion when CD34+ cell selection was followed by Campath-1M treatment. Recoveries of CD34+ cells, CFU-GM and BFU-E following double depletion using CD34+ cell selection plus CD2+ cell depletion were 28, 25 and 17% as compared to 20, 18 and 16% when CD34+ cells were treated with Campath-1M. The unadsorbed fraction contained 85% of the original T cells, from which donor leukocyte infusions in the range of 10(5) to 10(7) CD3+ cells per kg body weight of the recipient were harvested. Despite the advantages of component allografts, the loss of stem/progenitor cells may restrict sequential TCD steps unless single BM harvests are supplemented and/or replaced with mobilised PBSCs.

Original publication

DOI

10.1038/sj.bmt.1701296

Type

Journal article

Journal

Bone Marrow Transplant

Publication Date

07/1998

Volume

22

Pages

117 - 124

Keywords

Alemtuzumab, Antibodies, Monoclonal, Antibodies, Monoclonal, Humanized, Antibodies, Neoplasm, Antigens, CD34, Bone Marrow Purging, Bone Marrow Transplantation, Hematopoietic Stem Cell Mobilization, Hematopoietic Stem Cell Transplantation, Humans, Immunosorbent Techniques, Lymphocyte Depletion, T-Lymphocytes, Transplantation, Autologous, Transplantation, Homologous