Plastic-adherent progenitor cells in mobilized peripheral blood progenitor
cell collections
MA Scott, JF Apperley, HK Jestice, DM Bloxham, RE Marcus and MY Gordon
Department of Haematology, Addenbrooke's NHS Trust, Cambridge, UK.
The use of peripheral blood progenitor cells (PBPC) to reconstitute
hematopoiesis after high-dose chemoradiotherapy is now commonplace in the
treatment of malignancies. Attempts to characterize these cells have
concentrated primarily on their phenotype and their content of clonogenic
colony-forming cells (CFC). We have used a plastic-adherent delta (P delta)
assay system to evaluate the quantity and quality of more primitive cells
in addition to the conventional measurements of CFC and CD34-positive
cells. The leukapheresis products from 20 patients mobilized using
cyclophosphamide (Cy) and granulocyte colony- stimulating factor (G-CSF)
were examined for progenitor cell content. The mean number of mononuclear
cells (MNC), colony-forming units- granulocyte/macrophage (CFU-GM), and
CD34-positive cells from two leukaphereses per patients were 7.9 x
10(8)/kg, 47.3 x 10(4)/kg, and 10.5 x 10(6)/kg, respectively. The mean
number of P delta progenitors was 9.3 x 10(4)/kg. Limiting dilution
analyses showed the frequency of P delta progenitors in PBPC to be between
1 and 5.3 per 10(5) MNC and that each P delta progenitor has the
proliferative capability to generate an overall mean of 4.5 CFU-GM. Of the
20 patients, 16 underwent autografting with PBPC alone. Fifteen patients
engrafted neutrophils and platelets within 16 days. One patient had delayed
engraftment associated with inadequate etoposide clearance. Statistical
analysis showed a strong correlation between numbers of CFU-GM and CD34
positivity. The numbers of plastic-adherent P delta progenitor cells did
not correlate with CFU-GM or CD34-positive cells. We conclude that the
plastic-adherent P delta progenitor cell assay is capable of measuring
primitive hematopoietic cells and that it may be useful for the
investigation of primitive progenitors in PBPC harvests.
Volume 86,
Issue 12,
pp. 4468-4473,
12/15/1995
Copyright © 1995 by The American Society of Hematology
