The influence of the feeder cell line EL08.1D2 on the transition from CD56⁺CD94^–CD117^high to CD56⁺CD94⁺CD117^low/–. (A) At day 21 (±3) of culture, CD56⁺CD94^–CD117^high, CD56⁺CD94^low/–CD117^low/–, and CD56⁺CD94⁺CD117^low/– populations were FACS sorted and cultured for 1 week on either the fetal liver cell line (EL08.1D2) and cytokines (IL-7, IL-15, SCF, and FLT3L) or in media containing the cytokines alone. After 1 week in culture, the sorted populations were analyzed by FACS. Shown are the results after gating on the CD56⁺ fraction. Results were representative of more than 3 experiments. (B) The percentage of CD56⁺CD94⁺CD117^low/– cells detected after 1 week of culture either in the presence or absence of EL08.1D2. Shown are the results from 3 consecutive experiments (2 donors/experiment) where cells were sorted as in panel A and then cultured in cytokine containing media either without (white) or with (gray) EL08.1D2. Horizontal bar represents average and P is the result of a paired t test. (C) FACS-sorted CD56⁺CD9^–CD117^high cells (20 000) were cultured in triplicate with cytokines alone (left) or with cytokines and the stromal cell line EL08.1D2. Contact with the stromal cell line was either prevented with a transwell (middle) or allowed (right). Values represent the average number (+SD) of CD56⁺CD94⁺CD117^low/– cells detected after 1 week of culture by FACS. Shown are the results from a single donor, representative of 6 individual donors.