TSLP promotes the expansion and the differentiation of EPLMs, and DN1 and DN2 cells in vitro. (A) Absolute cell numbers harvested after a 7-day culture period of EPLMs (B220⁺ CD19⁻ NK1.1⁻ CD117⁺ CD93⁺) on either OP9 or OP9-DL1 cells in the presence of TSLP or IL-7, or without additional cytokine. (B) The percentage of CD19⁺ B220⁺ B cells, DN1 (CD25⁻ CD44⁺), DN2 (CD25⁺ CD44⁺), and DN3 (CD25⁺ CD44⁻) T-cell precursors is shown. Data shown here are from 1 representative experiment of 2. (C) Sorted DN1 (CD25⁻ CD44⁺ CD117^high) or DN2 (CD25⁺ CD44⁺ CD117^high) cells were plated on OP9-DL1 in the presence of TSLP or IL-7, or without additional cytokine. Absolute cell numbers were calculated after 7 days of culture. Flow cytometric analysis of (D) DN1 or (E) DN2 cells cultured for 7 days on OP9-DL1 in the presence of TSLP or IL-7. Data shown here are from 1 representative experiment of 2.