Expression of CD122 (IL-2/15Rβ) protein and IL-15R mRNA on CD34⁺ HPCs after culture in FL or KL. (A) Flow cytometric analysis of CD122 on freshly isolated CD34⁺HPCs (day 0) or CD34⁺ HPCs cultured in FL or KL for 10 days. The percentage of CD34⁺CD122⁺ cells (gated population) is indicated for each condition. (B) RT-PCR for IL-15R mRNA transcript expression. CD34⁺ HPCs from 2 donors were examined for IL-15R on day 0 (lanes 1 and 4), day-10 culture in KL (lanes 2 and 5), day-10 culture in FL (lanes 3 and 6), and 10-day culture in FL followed by culture in IL-15 for 14 days (lane 7). Lane 8 was H₂O control. RT-PCR analysis was performed as described in Materials and Methods.