CD34⁺ CD38^- and CD34⁺ HLA-DR^- cells in BM stem cell grafts correlate with short-term engraftment but have no influence on long-term hematopoietic reconstitution after autologous transplantation

Background: Prior studies have demonstrated that relatively immature hematopoietic stem cells, including CD34⁺ CD38^- and CD34⁺ HLA-DR^- subsets, correlate with short-term hematopoietic reconstruction (SHR) after transplantation. The aim of this study was to investigate whether these immature CD34⁺ subsets also correlate with long-term hematopoietic reconstitution (LHR) in recipients of ABMT. Methods: We examined stem cell grafts from 58 patients with B-cell lymphoma or CLL who underwent ABMT after myeloablative conditioning. We determined whether total mononuclear cell dose (MNC), colony-forming unit-granulocyte-monocyte (CFU-GM), CD34⁺ cell dose and CD34⁺ cell subsets (CD34⁺ CD38^- and CD34⁺ HLA-DR^-) were associated with SHR and/or LHR. Time to neutrophil engraftment (TNE) and time to platelet engraftment (TPE) were used to measure SHR, while platelet counts at day 100 and 1 year post-ABMT were used as indicators for LHR. Results and discussion: CD34⁺ cell dose and CD34⁺ cell subsets were significantly associated with SHR. However, at day 100 and 1 year post-transplant only total CD34⁺ cell dose was associated with LHR. The association of total CD34⁺ cell dose with LHR persisted after adjusting for age, sex and disease. None of the CD34⁺ cell subsets analyzed showed evidence of significant association with LHR.