Lack of modification of neutrophil survival by in vivo administration of rhAPC. Analysis of apoptosis and necrosis in neutrophils isolated 16 hours after endobronchial LPS-instillation from volunteers who received rhAPC (•) or placebo (○). Solid bars represents the median value for each condition. (A) Effect of rhAPC on spontaneous apoptosis. Histone-bound DNA isolated from unstimulated BAL (left) and blood (right) neutrophils in volunteers who received rhAPC, expressed as a ratio to histone-bound DNA isolated from LPS-stimulated blood neutrophils (apoptosis index), n = 4 for rhAPC and n = 7 for placebo. (B) Effect of rhAPC on neutrophil necrosis. The percent of unstimulated BAL neutrophils (left) and unstimulated and LPS-stimulated blood neutrophils (right) that underwent necrosis after 4 hours of culture was measured by release of LDH, expressed as a percent of the total LDH content of an equal number of neutrophils; n = 8 for rhAPC and n = 8 for placebo. Exposure to rhAPC did not significantly modify spontaneous apoptosis or necrosis in BAL or blood neutrophils, as analyzed by the Wilcoxon unpaired exact test. U indicates unstimulated; L, LPS-stimulated.