Effect of various cytokines on the survival and proliferation of FACS sorted CD34⁺lin⁻Flt3^high versus CD34⁺lin⁻Flt3^low cells in liquid suspension culture. Ten thousand Flt3^high or Flt3^low cells were cultured in RPMI containing 10% FBS and the designated cytokines, as described in Materials and Methods. Cells were counted by trypan blue exclusion. (A) and (B) time course of proliferation. Numbers shown are mean values of three independent experiments. The combination of FL plus five growth factors is shown separately in (B), because it would be off-scale in (A). (C) Fold expansion of sorted cells after 9 days in suspension culture in the same three experiments. The bars show cell expansion as the mean number of live cells per input cell. (A) (▤) Flt3 low; (▩) Flt3 low + FL; (□) Flt3 low + FL + KL; (▪) Flt3 low FL + KL + IL-3; (⦵) Flt3 high; (◍) Flt3 high FL; (○) Flt3 high FL + KL; (•) Flt3 high FL + KL + IL-3. (B) (□) Flt3 low; (○) Flt3 high. (C) (▨) FL + KL, IL-3 + GM-CSF + Epo; (▩) FL + KL + IL-3; (▨) FL + KL; (▧) FL; (▪) medium only. Error bars indicate the standard errors.