STERICALLY STABILIZED PHOSPHOLIPIDS ATTENUATE HUMAN NEUTROPHILS CHEMOTAXIS IN-VITRO

The purpose of this study was to determine whether sterically stabiliz ed liposomes (SSL) and poly(ethylene glycol)-distearoylphosphatidyleth anolamine (PEG-DSPE) attenuate polymorphonuclear neutrophils (PMNs) ch emotaxis in vitro and, if so, whether incorporation of vasoactive inte stinal peptide (VIP), a pleiotropic neuropeptide, on the surface of SS L amplifies SSL-induced responses. Using a modified blind-well chamber chemotaxis assay, we found that N-formylmethionyl-leucyl-phenylalanin e (FMLP; 0.1 mu M) and zymosan opsonized with purified human complemen t (2x10(9) yeast wall particles/ml) elicit significant human PMNs chem otaxis (95+/-9 and 103+/-3 cells/high power field; p<0.05). These effe cts are significantly attenuated by SSL and PEG-DSPE (p<0.05). By cont rast, aqueous VIP and VIP on SSL have no significant effects on FMLP- and zymosan-induced responses. We conclude that certain sterically sta bilized liposomes and phospholipids attenuate human PMNs chemotaxis in vitro and that VIP does not modulate this response.