T-cell and B-cell reconstitution was studied in nine patients who received fluorescence activated cell sorter (FACS)-sorted autologous CD34+ hematopoietic progenitor cells (HPC). The mean numbers of T cells (CD3+), B cells (CD19+) and CD34+ HPC administered to each patient were .004, .002, and 1.8 × 106 cells/kg, respectively. After high-dose myeloablative chemotherapy (busulfan, cyclophosphamide, etoposide) CD34+ HPC were infused and lymphoid reconstitution was monitored using flow cytometry and reverse transcriptase-polymerase chain reaction (RT-PCR) amplification of VDJ T-cell receptor (TcR) sequences. Restoration of normal numbers of peripheral blood T cells and B cells among recipients of FACS-sorted CD34+ HPC was delayed compared to recipients of non-T-cell–depleted PBSC autografts. In both patient groups, the circulating T cells were primarily CD4−, CD8+, αβ TcR+, and CD45RO+, CD45RA− during the first 2 months after transplant. Subsequent increases in the frequency of CD45RA+ CD45RO− T cells occurred at 2 to 3 months after transplant, suggesting maturation of CD34+hematopoietic progenitors to “naive” T cells. Analysis of the TcR repertoire after hematopoietic reconstitution demonstrated decreased diversity of Vβ TcR expression associated with global decreases in the absolute number of total peripheral blood T cells and most Vβ TcR+ subsets. Three of nine recipients of FACS-sorted CD34+ HPC demonstrated significant increases in the percentage of γδ+ peripheral T cells and CD5+ B cells at 3 to 9 weeks after transplantation, and all patients had transient oligoclonal expansions of T cells expressing specific Vβ TcR. Transplantation with highly purified CD34+ HPC results in reduced diversity of the peripheral T-cell repertoire during the early post-transplant period compared with patients receiving unmanipulated or MoAb-depleted transplants.

Neutrophil, monocyte, natural killer- and B-cell number and function are rapidly restored after bone marrow transplant (BMT), whereas T-cell reconstitution is often quite delayed. Our hypothesis was that V beta T-cell receptor (TCR) repertoire diversity among recipients of allogeneic BMT is influenced by the expression of major and minor HLA antigens in the host. The study population comprised unmanipulated and CD34(+)-selected allogeneic bone marrow grafts, autologous peripheral blood stem cell transplants and recipients of volunteer unrelated donor (VUD) bone marrow transplants. Using flow cytometry, the relative frequencies of 18 V beta TCR families were determined and ranked for each time point studied. Comparisons and correlations were made between paired blood samples obtained within a single patient over time, and between donors and their recipients. The pattern of the V beta TCR repertoire from allogeneic recipients and their HLA-matched donors was very similar, with a correlation coefficient (CC) of 0.59. This similarity was not as marked in VUD pairs (CC = 0.32). By 3 months after transplant, the pattern of the V beta TCR repertoire in recipients of HLA-matched sibling transplants was more similar to the pattern seen in pretransplant recipients than to the donor pattern (CC = 0.40 vs. 0.31). Our data suggest that both major and minor HLA antigens influence V beta TCR repertoire diversity and reconstitution after BMT.

T-cell and B-cell reconstitution was studied in nine patients who received fluorescence activated cell sorter (FACS)-sorted autologous CD34+ hematopoietic progenitor cells (HPC). The mean numbers of T cells (CD3+), B cells (CD19+) and CD34+ HPC administered to each patient were .004, .002, and 1.8 × 106 cells/kg, respectively. After high-dose myeloablative chemotherapy (busulfan, cyclophosphamide, etoposide) CD34+ HPC were infused and lymphoid reconstitution was monitored using flow cytometry and reverse transcriptase-polymerase chain reaction (RT-PCR) amplification of VDJ T-cell receptor (TcR) sequences. Restoration of normal numbers of peripheral blood T cells and B cells among recipients of FACS-sorted CD34+ HPC was delayed compared to recipients of non-T-cell–depleted PBSC autografts. In both patient groups, the circulating T cells were primarily CD4−, CD8+, αβ TcR+, and CD45RO+, CD45RA− during the first 2 months after transplant. Subsequent increases in the frequency of CD45RA+ CD45RO− T cells occurred at 2 to 3 months after transplant, suggesting maturation of CD34+hematopoietic progenitors to “naive” T cells. Analysis of the TcR repertoire after hematopoietic reconstitution demonstrated decreased diversity of Vβ TcR expression associated with global decreases in the absolute number of total peripheral blood T cells and most Vβ TcR+ subsets. Three of nine recipients of FACS-sorted CD34+ HPC demonstrated significant increases in the percentage of γδ+ peripheral T cells and CD5+ B cells at 3 to 9 weeks after transplantation, and all patients had transient oligoclonal expansions of T cells expressing specific Vβ TcR. Transplantation with highly purified CD34+ HPC results in reduced diversity of the peripheral T-cell repertoire during the early post-transplant period compared with patients receiving unmanipulated or MoAb-depleted transplants.