International Journal of Cell Cloning, Vol 6, 45-59, Copyright © 1988 by AlphaMed Press
Granulocyte-monocyte progenitor cells from human peripheral blood: modulation of growth in vitro by T lymphocytes and monocytes
DC Dooley, P Law and P Alsop
American Red Cross Biomedical Research and Development Laboratory, Rockville, Maryland 20855.
Cell fractionation techniques have been used for the purification and
characterization of hematopoietic cells present in peripheral blood and
bone marrow. Following fractionation, the distribution of hematopoietic
cells is frequently determined by the granulocyte-monocyte colony- forming
unit (CFU-gm) assay. In this study, we questioned whether the purification
process itself altered the sensitivity of the CFU-gm assay through changes
in the accessory cell populations. Experiments showed that following T cell
depletion, the cloning efficiency of CFU-gm was suboptimal, since the
addition of autologous T lymphocytes was stimulatory, even when the
concentration of conditioned medium was optimal. In contrast, growth of
CFU-gm was inhibited by monocytes, both in the presence and absence of T
cells. Sensitivity to monocyte-derived inhibition occurred at significantly
lower monocyte concentrations when T cells were present. Thus, stem cell
purification techniques which deplete T lymphocytes or enrich monocytes
have an adverse effect on the cloning efficiency of peripheral blood
CFU-gm. This study presents culture techniques capable of circumventing
these problems.
