[Human polymorphonuclear neutrophils (PMN) induce lipopolysaccharide (LPS) liberation from gram-negative bacteria]

Bacterial lipopolysacharride (LPS) is the major membrane component of Gram negative bacteria. It is a potent pleiotropic stimulus for the immune system frequently associated with septic syndrome or septic shock. The detoxification of LPS in Gram negative sepsis is one of the important problems to resolve in clinical treatments. In this study we compare the capacity of polymorphonuclear neutrophils (PMN) in LPS detoxification in two different situations: a) when LPS is offered to PMN as an isolated molecule; b) when the LPS offered is part of the whole Gram negative bacteria (E. coli 0111:B4). Our results show that PMN are able to inhibit the capacity of LPS to produce TNF-alpha. However, when whole bacteria, instead of LPS, are incubated with PMN, an enhancement in the production of tumor necrosis factor alpha (TNF-alpha) is observed. The bacterial overburden of PMN is not the reason for the spread of LPS after PMN incubation. Our conclusion is that PMN have a dual capacity to deal with LPS, either inactivating or releasing it depending on how it is offered.