Abstract

The CD34 antigen is a 115 kDa glycoprotein that marks 1%-4% of human bone marrow cells, including virtually all committed progenitor cells and long-term reconstituting stem cells. The selection of CD34+ cells may be useful in several areas of clinical stem cell transplantation, including purging of tumor cells, T cell depletion, stem cell expansion and gene therapy. Using immunomagnetic beads method (Isolex-50TM), we report hereby the first two Korean experiences of CD34+ selected peripheral blood stem cell (PBSC) transplantations. As a mean of tumor cell purging, CD34+ cells were positively selected from mobilized PBPCs and infused to a 5-year-old girl with a relapsed stage IV neuroblastoma with resultant early short-term trilineage hematopoietic recovery. In the second patient with chronic myelogenous leukemia who showed poor graft function after having underwent an initial partially-matched bone marrow transplant, CD34+ selected allogeneic PBSC transplantation was attempted to reduce the likelihood of inducing graft-versus-host disease. Augmentation of marrow function was noted with infused PBSCs which were depleted of T cells to the degree of log3.65. As CD34+ selected PBSCs are capable of restoring hematopoietic recovery after high dose therapy, further development of selection technique to ensure high purging efficiency without significant loss of stem cells and further identification of best mobilizing and conditioning regimens are required in this new field of clinical transplantation.

• Keywords: CD34; Peripheral blood stem cells; Stem cell transplantation; Immunomagnetic beads; Purging T-cells; Neuroblastoma; Craft-versus-host disease: chronic myelogenous leukemia