Predictors of high yield and purify of CD34(+) cell-selected PBPC, collected from patients with multiple myeloma.

BACKGROUND: Wide ranges i n cell recovery and purity may be observed following CD34(+) cell selection of mobilized HPC componetns. Characteristics of the mobilized HPC, associated with isolation of a high CD34(+) cell yield and purity following cell selection, have yet to be defined. METHODS: Cell number and purities were determined before and after 56 CD34(+) cell-selection procedures, performed using the CellPro Ceprate SC system from April 1997 to February 1998. HPC were collected from 28 patients with multiple myeloma, following cyclophosphamide (60mg/kg) and G-CSF (10microg/kg) mobilization. RESULTS: A medium of 47.9% (range 1.5-109.6%) CD34(+) cells were recovered in the enriched (ENR) fraction. A linear correlation existed between total CD34(+) cells in the ENR fraction and total CD34(+) cells in the START fraction (R2=0.93); there was a logarithmic correlation between CD34 ENR fraction purity and START fraction purity (R2=0.73). A START CD34(+) cell purity > 0.42% improved purity in the ENR fraction. A median of one (range one to nine) procedure was required to isolate 2 x 10 6 CD34(+) cells/kg. Three patients pretreated with alkylating agents failed to mobilized adequate numbers of HPC. DISCUSSION: Isolation of highly purified CD34(+) cell-selected components using the Ceprate SC system in dependent on the CD34(+) purity of the lekapheresis component collected. Mobilization regimens should be used to maximize CD34(+) cell purity in stem cell authografts if CD34(+) cell selection is to be performed. Similar strategies should be used to evaluate other cell-selection devices as they become available.

Sequential CD34+ and CD4+ cell selection from leukapheresis components.

We tested the feasibility of sequential selection of CD34+ and CD4+ cell-enriched fractions from aliquots of five autologous leukapheresis components. CD34+ cells were selected from a median 8.0 x 10(8) mononuclear cells using the CellPro CEPRATE LC cell separation system. All cells in the CD34-depleted fraction (median 4.8 x 10(8), range 0.6-10.0 x 10(8) were then incubated with the appropriate antibodies for CD4+ cell selection and passed through a second LC column. Median target cell purities of the CD34+ cell-enriched fraction and CD4+ cell-enriched fraction were 90.5% and 86.0%, respectively. This study demonstrates that high purity CD34+ and CD4+ cell-enriched fractions can be isolated sequentially from leukapheresis components. In addition, CD8+ lymphocytes, implicated in graft-versus-host disease, were depleted in the course of both positive selection procedures. This approach could decrease the number of donor procedures by providing separate CD34(+)-enriched and CD4(+)-enriched populations for allogeneic peripheral blood progenitor cell transplantation and subsequent donor lymphocyte infusion from the same leukapheresis component.