Interaction of liposomes with polymorphonuclear leukocytes: I. Studies on the mode of interaction

Abstract

Summary Amphipathic long chain anions (dicetylphosphate) or cations (stearylamine) were inserted into the lipid lamellae of multilayered lecithin-cholesterol liposomes so as to obtain liposomes with varying surface charge. These liposomes were then analysed with respect to their interaction with polymorphonuclear leukocytes (PMN cells) at 37°C. The different liposomes showed different tendencies to associate to the cells: the more negatively charged, the greater the tendency to associate. The association was insensitive to metabolic inhibitors and proceeded without activation of the hexose monophosphate shunt. It was not influenced by omitting divalent cations from the medium. However, lowering the temperature below 30°C and further down inhibited the association. The kinetics of the association process suggests that the presence of dicetylphosphate on the liposome surface increased the maximal rate of association, whereas lowering the temperature decreased the accessibility to appropriate receptor sites in the PMN cell membrane. The results lend support to the hypothesis that controlled manipulations of the liposome composition may be used to engineer the introduction of lipids into PMN cells by different rates and mechanisms. This should have relevance to the possible modification of PMN cell behavior by introduction of components derived from liposomes.