Figure 2.

Id2^−/− fetal thymocytes give rise to T cells but not NK cells in IL-2-supplemented fetal thymus organ culture. Lin⁻CD44⁺CD25⁻ FT cells at 14 dpc were sorted, and 100 cells were cultured with a dGuo-treated FT lobe (B6Ly5.1) in the presence of IL-2 (25 units/ml), IL-7 (50 units/ml), and stem cell factor (10 ng/ml). After 10 days of culture, cells in each well were analyzed by flow cytometry. Representative flow cytometric profiles for expression of indicated markers on Ly5.1⁻ cells were shown. Cell recovery was 2.4 × 10⁴, 3.0 × 10⁴, and 2.0 × 10⁴ cells for Id2^+/+, Id2^+/−, and Id2^−/−, respectively.