JAK3-AV–expressing T cells show decreased apoptosis and increased Bcl-2 expression. (A) Flow cytometric analysis of intracellular Bcl-2 levels in 3 different thymocyte populations (DP and SP) of JAK3-WT (shaded histogram) versus JAK3-AV (open histogram) animals. Bottom panel shows mean fluorescence intensity of the Bcl-2 signal normalized against an isotype control antibody in thymus and blood of JAK3-WT (■) and JAK3-AV (□) mice. All analyses are gated on GFP; data represent the average and standard deviation of 4 independent experiments. (B) Effect of JAK inhibitor I on Bcl-2 levels in CD8 SP thymocytes shown as a histogram and as bar graphs representing the mean and standard deviation of 2 independent animals for each group performed in duplicate. (C) Annexin-V staining for assessment of apoptosis levels in JAK3-WT versus JAK-3 AV CD8⁺ thymocytes. Analyses are gated on GFP⁺CD8⁺7-AAD⁻ thymocytes. Bar graphs represent the mean and standard deviation of at least 2 independent experiments each performed in duplicate.