Table 2.

Effect of hGM-CSF on single primitive hematopoietic progenitors

Cytokines	Positive for proliferation	Total CFU-Mix produced
SCF	0 /8	0
IL-6	0 /8	0
IL-6 + sIL-6R	0 /8	0
IL-11	0 /8	0
hGM-CSF	0 /8	0
IL-6 + SCF	3 /32 (9.4%)	30
IL-6 + sIL-6R + SCF	7 /31 (22.6%)	80
IL-11 + SCF	3 /21 (14.3%)	18
hGM-CSF + SCF	19 /31 (61.3%)	378

Single Lin⁻Sca-1⁺c-kit⁺CD34⁻ cells were obtained by clone-sorting of BM cells of the chimeric receptor transgenic mice and individually incubated with cytokines in a serum-free suspension culture. On day 6, each well was checked for the presence of proliferated cells. After three washes with α-medium, the proliferated cells in each well were individually replated into methylcellulose media containing IL-3, IL-6, SCF, Epo, and MDGF to examine the number of CFU-Mix. Data are from a single experiment, and similar results were obtained in two additional experiments.