Interaction of liposomes with polymorphonuclear leukocytes: II. Studies on the consequences of interaction

Abstract

Summary Polymorphonuclear leukocytes were incubated at 37°C with liposomes composed of phosphatidylcholine, cholesterol and dicetylphosphate and the cells obtained characterized with respect to properties that would disclose a modification of their surface properties. The cells excluded Trypan blue, did not leak 51 Cr-labelled cytoplasmic proteins and responded as control cells to concanavalin A (ConA) with an increased HMS activity. Their volume was increased as revealed by the pulse-height distribution at electronic counting. The partition of the cells in aqueous biphasic systems containing polymers with covalently bound ligands showed that their negative surface charge density and their liability to hydrophobic interaction were decreased. The cells showed a reduced capacity to phagocytose S. typhimurium 395 MR 10 and S. typhimurium 395 MS opsonized with hyperimmune anti-MS IgG and a decreased random mobility. This suggests that the presence of exogenous lipid affects the molecular organization providing attachment of a particle to be phagocytosed and alters such surface properties of the cell that are linked to its motility. The results support the hypothesis that liposomes may be used to modify the physico-chemical surface properties of polymorphonuclear leukocytes and so their essential biological functions.