Lipopolysaccharide, tumor necrosis factor-α, and IL-1β prevent programmed cell death (apaptosis) in human peripheral blood monocytes

Our results clearly indicated that monocytes die by PCD when cultured without stimulation. Death was associated with fragmentation of DNA into integer multiples of ∼ 200 bp, a decrease in cell size, condensation of the nucleus and cytoplasmic organelles, and membrane blebbing, all of which are cardinal features of PCD. Addition of Escherichia coli LPS, a potent monocyte activating agent, in concentrations as low as 0.1 ng/ml caused a marked increase in monocyte survival and prevented DNA fragmentation