LIPOPOLYSACCHARIDE-STIMULATING, GRANULOCYTE-MONOCYTE COLONY-STIMULATING FACTOR AND PENTOXIFYLLINE-MEDIATED EFFECTS ON FORMYL-METHIONYL-LEUCINE-PHENYLALANINE-STIMULATED NEUTROPHIL RESPIRATORY BURST IN THE ELDERLY

The impairment of superoxide anion (O-2(-)) generation by aged polymor phonuclear cells (PMN) stimulated with formyl-methionyl-leucine-phenyl alanine (FMLP) has been reported. In this work the effect of lipopolys accharide (LPS), granulocyte-macrophage colony stimulating factor (GM- CSF) and pentoxifylline (POF) pretreatment on FMLP-triggered neutrophi l oxidative metabolism in a group of healthy elderly individuals, was investigated. Results provide evidence that LPS and/or GMCSF priming w as able to enhance Oi production in old PMN, even if values were still lower than those observed in similarly-treated young cells. Moreover, even if the lag period was unaffected by inflammatory mediator treatm ent, the priming gave rise to a significant increase of maximum O-2(-) release rate. On the contrary, POF pretreatment led to a significant decrease of oxidative responsiveness in either unprimed or primed PMN suspensions. These findings suggest the occurrence of different mechan isms in the imbalance of FMLP-activated neutrophil oxidative responsiv eness during senescence. This may be of paramount significance for exp laining the augmented frequency of severe infectious diseases with adv ancing age. .