A, apoptosis and necrosis following treatment with 50 µM (13,6 µg/ml) and 100 µM (27,3 µg/ml) nimustine (ACNU). Fixation occurred 72 h after treatment. B, apoptosis and necrosis following treatment with 100 µM (19,4 µg/ml), 200 µM (38,8 µg/ml) and 250 µM (48,5 µg/ml) temozolomide. Fixation occurred 72 h after treatment. C, apoptosis and necrosis following treatment with mitomycin C. Fixation occurred after 48 h. D, apoptosis (determined by subG1) induced by acrolein in Treg, Th and CTL after 48 h. The abscissa points to the dose of acrolein and, on the top, the equivalent dose of mafosfamide, which is in the range of 0–2 µg/ml (compare with Fig. 2B). Data are the mean of at least three independent experiments. The solvent (DMSO for temozolomide) and the aqueous controls were not toxic if given without the drug.