Delay of PMN apoptosis by LPS, GM-CSF, and DEX, and LPS-induced degradation of IκBα. (A) Samples were incubated with buffer control, 100 ng/mL LPS, 20 ng/mL GM-CSF, and 10^–7 M DEX. Cells were harvested after 20 hours, permeabilized in ethanol, stained with propidium iodide, and assayed by flow cytometry. These experiments indicate significantly delayed apoptosis by LPS, GM-CSF, and DEX (n = 6, **P < .01). The values represent mean ± SEM. (B) The effect of 100 ng/mL LPS, 20 ng/mL GM-CSF, and 10^–7 M DEX on IκBα degradation was studied by Western blot (n = 3). PMNs were harvested at the indicated time points; cytoplasmic extracts were prepared and analyzed for IκBα. (C) For densitometric analysis of the IκBα expression, the optical density value of the first band (time point 0 minutes) was set 1.0 and the following time points represent the relative changes of IκBα intensity. Only LPS led to a significant degradation of IκBα after 60 and 120 minutes (**P < .01). ⋄ indicates LPS; ○, GM-CSF; and ▵, DEX.