Dose response effect of CD34⁺ and CD15⁺/CD14⁻ cells on stromal G-CSF production. From 10,000 to 100,000 CD34⁺ or CD15⁺/CD14⁻ cells were plated on stromal layers. SNs were obtained on day 4 and G-CSF levels were determined by ELISA. G-CSF levels shown as percent of stromal SN is 100%. Numbers within the figure indicate number of experiments. (A) The indicated numbers of CD34⁺ or CD15⁺/CD14⁻ cells were plated on stromal layers. Comparison between stroma and other conditions: *P < .05, ¶P < .02, ¥P < .001. (B) Combinations of CD34⁺ and CD15⁺/CD14⁻cells were plated together on stromal layers. Comparison between stroma and other conditions: *P < .05.