A through E: PI staining (A,D), CD4 versus CD8 expression (B,E), and FSC versus SSC profile (C,F ) of αβ TCR transgenic thymocytes uncultured (A through C), and cultured for 48 hours (D through F ). PI^low, PI^int, and PI^high cells (regions 1, 2, and 3) represented 97%, 0.5%, and 2.5%, respectively in (A), and 10%, 44%, and 46% in (D). (G through J): correlation between CD4 versus CD8 expression and PI staining levels in the live cell gate (R1), and in the apoptotic cell gate (R2) of 48-hour cultured thymocytes.