Colony formation from cord blood CD34⁺ cells by varying concentrations of FL in the presence of 100 ng/mL of IL-6 and 1,000 ng/mL of sIL-6R. 5 × 10² cord blood CD34⁺ cells were incubated in serum-containing culture, and the colonies were scored at day 14 of culture. The number of colonies increased dose-dependently to FL. The formation of total and erythroid/Mix colonies was most pronounced at 100 ng/mL of FL.