The effect of trichostatin A (A-C) on human eosinophil apoptosis in the presence of budesonide (1 μM; A), fluticasone (1 μM; B) or mometasone (1 μM; C). In (D-F) is shown the effects of HDAC inhibitors apicidin (D), MC1293 (E) and MS-275 (F) on eosinophil apoptosis in the presence of budesonide (1 μM). Apoptosis was assessed by flow cytometry measuring the relative DNA fragmentation in propidium iodide-stained cells. ** indicates P < 0.01 and *** P < 0.001 as compared with the respective control in the absence of HDAC inhibitors. Mean ± S.E.M. of 5-6 independent determinations using cells from different donors. The corresponding percentage of apoptotic cells in the absence of glucocorticoids and HDAC-inhibitors was 49 ± 3 (n = 25).