FIG. 6.

Decreased in vitro survival of DP thymocytes from Prep1^i/i mice. DP thymocytes from Prep1^i/i mice and their heterozygous littermate controls were stained with PE-conjugated anti-CD4, APC-conjugated anti-CD8, FITC-conjugated annexin V, and 7AAD ex vivo prior to FACS analysis. (A) A representative example of DP gated thymocytes is shown. (B and C) Survival kinetics of DP (B) or of CD4⁺ CD8⁺ SP thymocytes (C) from Prep1^i/i (i/i) mice and their heterozygous Prep1^+/i (+/i) littermate controls. Thymocytes (1 × 10⁶ cells per well in a 96-well plate) were incubated at 37°C and collected at various time points. For each time point, the total number of viable thymocytes and the percentage of DP thymocytes were determined (see Materials and Methods). In panel B, the data are expressed as the absolute number of surviving DP thymocytes; in panel C, the data are expressed as the percentage of viable CD4⁺ CD8⁺ thymocytes in each well.